My 2 cent worth of opinion.
1. No license yet then how to market and sell the property? Don't even mention to sign spa. Check with your own lawyer and see if anything fishy here.
2. Regulation actually don't allow developer to "forfeit" money before signing any spa. More so if the is no approval from government yet.
3. I believe for now if you can prove that you use that property for residential purpose then should be exempted from gst. But then the developer must prove la. On top of that you should sign a schedule H/G(I don't remember already but is some schedule la).

Hope this help