Sajdah-e-Tilaawat

Q: If I am learning a Surah with a sajdah off by heart, then do I have to do the same amount of sajdah tilawat as the amount of times I recite the aayat of sajdah? If I am making more than one sajdah tilawat then how would I do it? Is it the same as in namaz or do I have to do them all separately with intentions in between all of them because I have quite a few to do from before as well?

Tile becoming impure

Q: If I make a tile napaak as a piece of clothing with urine on it has touched it, if I do wudhu and my wet feet touches the tile, if my foot doesn't smell of urine nor does it turn yellow is my foot considered paak or napaak?

Reciting a portion Bismillah and Ameen loudly

Q: If in salah on my own, I am reciting out loud and I recite bismillah out loud, and half way through it I stop, and re-recite it silently, is my salah invalidated? Also, is it invalidated if I recite it out loud and complete the recitation of it out loud only to re-recite it silently? I also have the same question but instead of Bismillah, I recite ameen out loud. Does reciting ameen out loud invalidate the prayer? also, if it does, would rectifying the ameen out loud by reciting it again straight after silently, cause the prayer to be valid again? Another question I have is that during the salah, I said some of the takbeers out loud and others including possibly 'Sami Allahu liman hamida' silently. Would this inconsistency render my salah invalid?