Gst on real estate business

Dear Experts...

I am working for an real estate company. please provide clarification on the following:

1. How to raise invoice for Apartment (UDS & Construction)?

2. What is the rate of GST on ready built house (Completed house)?

3. What are the necessary documents to be get for completion certificate? we are not comes under CMDA purview. we are based on Tirunelveli Corporation area.

My advance thanks for your reply.

regards,

Subbiah