Confusion between gift deed and release deed

Hi there.we are residing in mumbai, india. i need guidance on execution of deed in correct way. my mother and i ( son ) have and own a residential premises in a chs in which we are joint owners ( % share of owneship ) is not mentioned any where. now my mother intends to withdraw her name and want me to be owner of entire residential premises. questions - 1. can she execute a gift deed to transfer her rights / shares to me or it has to be a release deed ? question 2 - which is the best easy, simple and cheapest option - as in maharashtra relative transfer of gift deed is just rs 200 and where if it is a release deed then it is 3% of market value . So if market value of entire premises is rs 80 lakhs as per collectrate valuation , then her proportion will be 80 lakhs x 50 % her share - so 40 lakhs and on such 40 lakhs - 3 % stamp duty - rs 1,20,000. question 3 - what will be income tax precussions in both the cases ? question 4 - currently ( i) son is not married, so if i want to put a clause that after such transfer from mother to son, and in future if the son die, then such title and ownership again goes to the mother and not to married wife ? can such clause be included in such deed at this point of time ? question 5 - if it a gift deed then in such deed - the entire property is mentioned or only her share is specifically mentioned for such transfer ( but how much % we both own is not mentioned any where ). question 6 - after execution of such deed, which is a more safe and legal document ?