Berakhot 26

What do you do if a sefer Torah is in a room where one is planning to have sex? How far does one need to distance oneself from feces or urine in order to say shema? On what does it depend? Can one say shema in a place where there is a bathroom that had never been used? A zav that had a seminal emission or a woman who was a nidda and then semen discharged from her body or a woman who has sex with her husband and then becomes a nidda - all these need several days before they can become pure - but can they and should they go to the mikveh before learning Torah? Or since they can't become pure yet, they can't go to the mikveh and therefore maybe Ezra's ordinance did not include these cases? Is the order in which the events happened important (first baal keri and then zav or the reverse)? Until what time can one pray the morning, afternoon, evening and additional (on holidays) prayer? Is there a contradiction between what it says in the minsha regarding the times and other sources?  How does this connect with laws of additional prayers that one can say if one forgot to pray - as one can make up the morning prayer in the afteronon? Were the prayers instituted by the fathers or were they set up as a replacement (or to correspond) to sacrifices?