The first is located at very beginning of Perek Hay (Chapter 5); the second begins at Perek Hay (Chapter 5), p'suk yud-aleph (verse 11) and continues through the end of the Perek.

1. Hashem spoke to Moses, saying:

2. "Command the Children of Israel that they shall expel from the camp everyone with tzaraas, everyone who has had a zav-emission, and everyone contaminated by a human corpse: 

3. Male and female alike shall you expel, to the outside of the camp shall you expel them, so that they should not contaminate their camps, among which I dwell."

4. The Children of Israel did so - They expelled them to the outside of the camp, as Hashem had spoken to Moses -- so did the Children of Israel do: 

First, I will provide the commentaries according to the Stone Edition Chumash: 

(1) Purification of the camp. To make their camp a worthy home for the newly erected Tabernacle and the Divine Presence [Shechinah] that had begun to rest among them, the Jews were cautioned to free their camp of ritual contamination [tumah] (Ramban). Consequently, this passage was transmitted to the nation on the first of Nissan, the day the Tabernacle became sanctified (Rashi). As explained in the notes to Leviticus, though physical factors are the immediate cause of ritual contamination, it is harmful to the spiritual standing of the person it affects and the place where it exists. Tumah and its laws are beyond human reason; the Sages characterize them as "decrees of the King." 

(4) Did so ... so did [they] do. The double expression alludes to the two groups that participated in carrying out the commandment: the Israelites who enforced the order and the contaminated people who left the camp willingly (Malbim). 

Rav Samson Raphael Hirsch goes into a great deal of explanation concerning all three points of tumah (impurity or contamination).  He begins by reiterating the arrangement of the camp.  The Sanctuary was in the center (the inner sphere), surrounded by the Kohanim and Levi'im (the inner circle), and finally the balance of the population (the outer circle).  His first point is that this commandment has nothing to do with expelling someone from the camp.  Rather, it has everything to do with preventing someone who is tameh (impure or contaminated) from coming in contact with the Sanctuary.  In Judaism, this concept of "gates" is seen in many places.  In other words, in order to prevent transgressing a given commandment, many times there are lesser rules that are in force so that the actual transgression can never be approached, let alone occur. 

Second, Rav Hirsch explains each of these states of tumah.  Tzaraat was somewhat like leprosy.  Unlike the disease today, it was brought about as a result of someone lowering their level of spirituality - usually through a transgression of some sort.  In the presence of God, the Hebrew people were on a much more elevated spiritual level than today.  Acts that lowered that in an individual resulted in tzaraat.  Unlike today's disease, this contamination could be removed by awaiting sundown (the beginning of the next day) and immersion in a mikveh.  Of course, with that, the tzaraat disappeared and the person re-entered the camp.  The zav-emission was a seminal emission.  This resulted from a lack of sexual purity and thus was considered to bring about a state of tumah.  Again, sundown and immersion in the mikveh removed the tumah state. 

Now we come to the perplexing one - coming in contact with a corpse.  Why did God set this up as a state of tumah?  To answer this, we have to return to the concept of separation.  In multiple places in the Torah, God declares that the Hebrew people shall be separate unto themselves.  Although this is most often used in terms of intermarriage, the commandment is far more extensive.  The surrounding nations worshipped the dead and, in some cases, elevated them to the level of deities.  For this reason, God placed this particular point in the Torah.  As was the case with tumah in the previous two examples, this too was rectified with sundown and immersion. 

Now we come to the other controversial point. 

12. "Speak to the Children of Israel and say to them - Any man whose wife shall go astray and commit treachery against him:

13. and a man could have lain with her carnally, but it was hidden from the eyes of her husband, and she became secluded and could have been defiled -- but there was no witness against her -- and she had not been forced:

14. and a spirit of jealousy had passed over him and he had warned his wife, and she had become defiled, or a spirit of jealousy had passed over him and he had warned his wife and she had not become defiled: 

15. The man shall bring his wife to the Kohen and he shall bring her offering for her, a tenth-ephah of barley flour; he shall not pour oil over it and shall not put frankincense upon it, for it is a meal-offering of jealousies, a meal-offering of remembrance, a reminder of iniquity:

16. "The Kohen shall bring her near and have her stand before Hashem:

17. The Kohen shall take sacred water in an earthenware vessel, and the Kohen shall take from the earth that is on the floor of the Tabernacle and put it in the water:

18. The Kohen shall have the woman stand before Hashem and uncover the woman's head, and upon her hands he shall put the meal-offering of remembrance -- it is a meal-offering of jealousies, and in the hand of the Kohen shall be the bitter waters that cause a curse:

19. "The Kohen shall adjure her and say to the woman, 'If a man has not lain with you, and you have not strayed in defilement with someone other than your husband, then you shall be innocent of these bitter waters that cause curse:

20. But if you have strayed with someone other than your husband, and if you have become defiled, and a man other than your husband has lain with you -- !':

21. "The Kohen shall adjure the woman with the oath of the curse, and the Kohen shall say to the woman, 'May Hashem render you as a curse and as an oath amid your people, when Hashem causes your thigh to collapse and your stomach to distend:

22. These waters that cause curse shall enter your innards to cause stomach to distend and thigh to collapse!' And the woman shall respond, 'Amen, amen.': 

23. "The Kohen shall inscribe these curses on a scroll and erase it into the bitter waters:

24. When he shall cause the woman to drink the bitter waters that cause curse, and the bitter waters that cause curse shall come into her:

25. "The Kohen shall take the meal-offering of jealousies from the hand of the woman; he shall wave the meal-offering before Hashem, and he shall offer it on the Altar:

26. The Kohen shall scoop up from the meal-offering its remembrance and cause it to go up in smoke on the Altar; after which he shall cause the woman to drink the water: 

27. He shall cause her to drink the water, and it shall be that if she had become defiled and had committed treachery against her husband, the waters that cause curse shall come into her for bitterness, and her stomach shall be distended and her thigh shall collapse, and the woman shall become a curse amid her people:

28. But if the woman had not become defiled, and she is pure, then she shall be proven innocent and she shall bear seed:

Rav Hirsch's comments to this particular section are quite lengthy.  Therefore, I'll summarize.  However, prior to that, there is something obvious that needs to be stated concerning the marital relationship.  In Judaism, there has never has the concept of "until death do us part."  The Torah has always accepted that not every marriage is a good marriage or "made in heaven."  As such, Judaism has always had "divorce" for the marriage that is not beneficial to either party. 

If a marriage is not working, if there is adultery, then divorce is the proper method for resolving the problem - not the method outlined above. 

This particular procedure was utilized only in very specific cases.  There are two very important points that must be covered.  First, the wife is the one who must request this, not the husband.  The Torah says the husband brings his wife before the Kohen.  However, it is at the wife's request.   Second, this is used in situations where there is gossip.  The example that Rav Hirsch uses states that the gossip resulted either from a situation where people may have suspected that the wife had been with another man (see verses 13 and 14) or because her attire was not modest enough for others.  This entire procedure is carried out in public.  Therefore, if there is loshon hara (gossip), it will be clear at the end that the woman is not guilty of the behavior being discussed which will put an end to the gossip and hopefully help people restrain from similar behavior in the future.  As an aside, if a woman were guilty of such behavior, surely she would request a divorce rather than this. 

Further, the Torah states "and there shall be a spirit of jealousy . . . “ In this particular instance, it is clear that the man does not want a divorce but would rather have things return to a healthy position - again, demonstrating that divorce is not the option being considered. 

There is a final point, and this procedure was sometimes requested for that purpose, which has nothing to do with unseemly behavior or loshon hara.  This is the final pasuk (verse) in this section: 

28. But if the woman had not become defiled, and she is pure, then she shall be proven innocent and she shall bear seed:

Notice the last five words - "and she shall bear seed."  Couples would come before the Kohen and have the procedure done to produce this outcome - children.