The Gemara is bothered by a contradiction in R' Yehuda's opinion. In the Mishna and Bra'aisa, he allows a Ba'al Keri to recite aloud the blessings before and after eating. (it seems that he doesn't hold of "Tevilas Ezra." Yet, the Mishan later clearly implies that R' Yehuda does require Baal Keri to immerse before learning/davening. The Gemara answers that although R' Yehuda holds of "tevilas ezra," it does restrict the baal keri from learning simple things like laws of Derech Eretz and simply reciting blessings is permitted.

There are varying opinions regarding the type of Torah a Baal Keri cannot learn. R' Yosei allows one to recite but not go in depth with Mishna. R' Yonasan allows him to even elaborate on a mishna but not a gemara. R' Nasan allows even Gemara as long Hashems's name is not recited. R' Yocahan Hasandler allows nothing at all. R" Akiva may not even allow him into the beis midrash. R' Yehuda allows the laws of Derech Eretz but he was personally stringent for himself.

R' Yehuda Ben Beseria holds a Baal Keri is allowed to learn Torah bc Torah is like fire and is impervious to contamination. This is the world's custom.

There was a leniency within Tevilas Ezra that instead of immersion in 40 seah, if 9 kabin is poured on the Baal Keri it allows him to study Torah. Some Rabbis did not teach this leniency publicly.

Even if Tevilas Ezra is technically gone, it is still good to be stringent and one merits longevity if they go to the mikvah. It also can help prevent sin.

There is a dispute if one can perform "tevilas ezra" in hot bathhouse.

Ezra originally instituted for healthy persons who willingly saw Keri to immerse in a mikvah. After, the Rabbis added that if it was not willingly, then 9 Kabin suffices. Then there is a dispute about a sick or weak person who willingly sees Keri is he needs immersion in 40 seah or 9 kabin suffices, and additionally, if a weak person unwillingly saw Keri if he needs 9 kabin or nothing at all.

There is a dispute if a Ba'al Keri who is reciting Torah for others should immerse in 40 seah. The 40 seah could be "Sh'euvin- drawn water" but there is a dispute if they may be in a vessel or in the ground.

Someone who realizes they are Keri in the middle of Shmone Esrei should continue praying but should shorten the Tefillah.

Someone in a mikvah who doesn't have enough time to get out of the mikvah and get dressed b4 the time for Shema will elapse can recite the Shema in the water

A person must be distanced 4 amos from excrement or urine when praying.

Someone who discovers excrement ahead of where they are praying should move ahead if possible or at least to the sides.

If one discovers excrement where they are praying and in a place they should have checked, the law is that the Tefillah doesn't count and they must pray again.

If one urinates during Tefillah, they must stop while the urine flows and only then continue. There is a dispute if one has to go back to beginning of Shmone esrei or resume from the spot they were up to.