(1) [a, b, c] It should be recited with tongue, it is not right to recite it with heart. [d] If it is four rakaat of fardh and you are praying it behind an imam, then you should keep silent in third and fourth rakaah, but if it is sunnah or nafl (optional) then you have to recite Surah Fatihah with any surah. [e] It should be recited with tongue.
(2) After reciting Al-Tahiyyat, having said one salam you should do two sajdah, then recite Al-Tahiyyat, durood and dua and turn your head for salaam to both sides.
(3) It is not mandatory.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband