what is BBMP approved apartment

[house_hunter]

Hi Friends,
Any apartment which is approved by CMC and now comes under BBMP

1) what are the potential problems if I buy flat in such apartment
2) where would the registration of this property happen? in BBMP?
3) would I get Khata from BBMP?
4) do I need to pay betterment charges to BBMP? any other charges?
5) would there be any issue in future since this is not BDA/BMRDA approved.. this would be only BBMP approved.

Kindly answer above mentioned queries.

Thanks a lot.
House_hunter.