Those things which render the Salaah invalid

Saying Aameen in one's heart in Salaah

Q: As far as I am aware, speaking intentionally or unintentionally will nullify the salaah and it will have to be re-prayed again according to the hanafi maddhab (although, if I am incorrect in my understanding then please correct me jazak Allah khayr). The question I would like to ask is that say for example, if I recite اَللَّهُمَّ رَ‌بَّنَا آتِنَا فِي الدُّنْيَا حَسَنَةً وَفِي الْآخِرَ‌ةِ حَسَنَةً وَقِنَا عَذَابَ النَّارِ‌ and in my heart I say Aameen but my tongue may move slightly unintentionally, however there is no sound of any letters coming out, can that be classed as speaking in Salaah?

Toes touching the ground in sajdah

Q: Majority of the time when I do sujood, my little toe doesn't touch the ground and perhaps the two besides it, but the big toe and one next to it  mostly do if not all do, so, is all toes touching the ground with pressure waajib/Fard, if so should one make movements in sujood or seating to ensure they touch the ground? Also I am not able to remember all the times this has happened, a lot though.