Builder Floor 2021 law

I purchased a builder floor 200sq yards central delhi from direct owner with collaborating with builder and the registration shows 25% share is mine. I got 25% share for top floor with roof rights. Total are 4 floors + stilt parking + basement. 1) As the building is not constructed after the completion i have to do partition deed, now how much amount is of partition deed and should i pay that or the builder is liable to do so? 2) as of 07/2021 there’s no underground water tank is it compulsory? Can we do it after the construction? As the builder is not willing to and rest 3 floors are not sold yet so most probably all 4 floors will together make a plan to built one after the completion. 3) the builder says parking is common area and 25% share is yours but there wont be written documents anywhere, so first is there any way i can registry my parking or mention it at time of partition deed. As there are 4 floors and approx only 5-6 cars can park inside how would all the 4 floors manage? 4) the layout of the floor is passed but the builder says you can remove or add any wall inside of your floor as in changing the position of washroom from centre of floor to lest or right side or even increase or decrease size of rooms. Only pillars can’t be changed. Is it legal? If not the floor is not yet constructed can i change the layout as per my choice what are the charges and process of revision of layout by only changing inside room size and position? 5) There’s a washroom on the roof but its not in layout, is it illegal? But as In my registry shows i have toP floor With roof rights, if i can’t make even a washroom why does it even mentions roof rights? What extra can be done over the roof? Which is legal as in official documents it shows roof rights Please mention other important laws one should always remember in 2021 while purchasing a builder floor. Thanks