Registry query - for loaned property

I am planning to purchase a builder floor in Green Field Faridabad, which is already built till 2nd floor, owner (Owner and builder are same) will get into redevelopment with stilt parking plus 4 floors, I am buying first floor, but now builder is saying he is having a loan on this property, pls help me 1. How he will demolish this building without bank permission. Whether NOC can be given by the bank? 2. How my registry will be done, as original papers is with the bank. 3. Do I have to wait till all the floors are sold for registry, or registry can be done only after paying the whole payment to bank. 4. Should I go ahead and buy this property?