Sajda-e-Sahw

Doubting the number of sajdahs performed

Q: I was praying and I got doubts about how many sajdahs I did and I was doing first the Tashahhud and I determined that I would do one more sajdah in case and I was reciting "Assalaamu alayka ayyuhannabeyyu.. " and around here or after "wa" I determined that I was going to do sajdah, but I added "wa Rahmatullaah" and then I stopped and proceeded to do sajdah (I did Sajdah-Sahw afterwards). But now I doubt that I did an "addition" that invalidates the salaah.

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?