Sajdah and Jalsah

Q: For males and females- where should the thumbs be kept in sajdah- in line with the ears or eyes?

Q: I would like to know, is it necessary to do sajda-e-sahw if we pray "Subhanarabiyal azim "only once in ruku instead of three times, also if we mistakenly pray "subhanarabiyalala" only once instead of three times in sajda?

Q: I have a question with regards to method of performing salaah. If one is performing salaah, whether alone or in jamaah, should the person recite his tasbeehat in a manner that the next person can audibly hear what he is reading or should the brother read it softly so that the next brother cannot hear what the brother is reading. 

Q: Should the feet be kept together or apart in sajdah? All this while I used to have it together until I read in the Majlis that there is no basis for it. What should I do?

Q: In sajdah if the two hands are placed on the ground but only a part of the palm and the tips of the fingers are touching the ground does this affect the salaat?

Q: Is it ok if I make English dua or Portuguese dua in sajdah in farz or nafl namaaz? One Aalim from Portugal said I can. After all, he is a learned Aalim, whats wrong if I follow him? All mazhabs are correct after all.

Q: If the toes slide slowly during sajdah (because of the khuffs) without it becoming seperated from the ground, is the sajdah and thus the salaah valid?

Q: What is the Hanafi proof for making the heels touch in sajda? Is this applicable to followers of other madhabs as well?

Q: What is the Sunnah method of going down in sajdah? Should we go down into sajdah without placing the hands on the knees, or go down with placing the hands on the knees?

Q: How long is it waajib for jalsah in salaah?