54F exemption on sale of multiple residential lands and investment into residential house

I had purchased 2 residential lands in 2000 and 2003 and have sold them in April 2021 and April 2022 (planned). All dates are registry dates.

• Land 1 sale price: 15L
• Land 2 sale price: 65L

I plan to invest these into purchase of residential flats and avail exemption under section 54F.

1. Is 54F exemption applicable if I pool the money from the 2 sales and buy a single flat of 80L?
2. Is 54F exemption applicable if I split the money into 40L + 40L for purchase of 2 separate flats in the same building (Jodi flats)?
3. For 54F exemption on investment into an under construction project, what milestone does the under construction project need to achieve in 3 years? [e.g. Does possession have to be granted?, or is a contract with the builder enough, or something else?]

I do not own any residential house currently under my name

Thank you