Those things which render the Salaah invalid

Q: While leading the salaah, I had a feeling that mazi may have been discharged, but was not sure. When I returned home, I found a slight wetness
at the tip of my private area, and it was only when I began to clean it that the mazi began come out. Now I am uncertain if it remained in the passage 
during salaah and began to come out as a result of walking, or if any came out during salaah. Firstly, will it be necessary for the congregation to repeat the salaah? Secondly, is this common, or is it a medical issue?

Q: In Tahajjud salah can we take the Quran and recite from it?

Q: My question is about "taqlid after amaal".

If a Hanafi after salaah, finds out his salaah was not valid according to the Hanafi madhab, but it is valid according to for example Hanbali madhab, can he follow that madhab and suffice with salaah he has prayed?

Q: What is amal-e-katheer?

Q: I was offering namaaz when I heard some sound from my stomach. I am 90% sure it wasn't gas but as I am too much surrounded by waswasas I began to think I may have broken my wudhu but I continued with my namaz. My question is was my namaaz valid?

Q: While performing sajdah, if one lifts his feet off the ground, will the Salaah break?

Q: If you are praying and notice that you are preventing someone from going past you because of your prayer, is it permissable in this case to move slighly (e.g. 1 step) to give the person space to pass? Or will this be like obeying a command from outside the prayer, hence invalidating it?

Q: If a shafi muqtadi who is making simaa'at from the Quraan gives luqma to a shafi imaam and the imaam accepts this luqma, ( which if I am not mistaken is permissible according to shawaafi as it is not amal e katheer according to them) what will be the status of the iqtidaa of a hanafi in that jamaat?

Q: If one takes wudhu and on the mustache there will stay drops of water and during salaah few drops do enter the mouth, does the salaah brake?

Q: If one is sick with fever and has a running blocked nose, if such person gets up from sajdah and because he could not breath properly in sajdah when he stands when releasing breath a sound like a short "eh" comes out unintentionally, does this break the prayer?