Is it OK to split a large 3BHK apartment into two smaller 2BHK units for rental purpose?

Q: I have seen an apartment on 2nd Floor of an under construction G+3 building, constructed on 60x40 site. Only 1 apartment per floor. BBMP approval is for 4 units (Two 2BHKs on G floor, One 3BHK each on 1st and 2nd). G+2 plan is approved by BBMP, the top floor is not approved.
I have the following questions:
1) Can apartments built on 60x40 site be seperately sold or the whole building has to be sold?
2) The builder as constructed ~700sft excess per floor (2050sft is build up area per apt per floor. 1400sft is in approved plan, rest 700sft is excess)
3) Can I split the large 2050sft 3BHK flat into two 2BHK 1050sft flats, of which one can be rented? But 2050sft flat as a whole would be sold and registered in my name.
What are the implications of buying the above 3BHK flat with the said deviations and splitting it into two units for rental purpose only (not for sale)? What is the total % of deviation in the above case?