Hi,
As to the getting the land rezoned before buying it can be tricky. If you got the land rezoned, the seller who still owns the land can argue it is worth more. It comes down to risk vs purchase price.
I purchased agricultural land that I am in the process of rezoning. I am making individual 5 acre lots creating a total of 7 lots. This land per current zoning requires 5 acre average. So I am not actually asking to do more with the land then what is allowed. Others in my area have been successful in my region in getting land rezoned to higher density. But the town has now caught on and is against rezoning any additional lands. So you can caught up in local politics. But it seems that the town is supportive of your goals. Hope that helps just a little!
The upside to that risk is that it can be very lucrative. Of my 7 lots, I will have more than broken even after two lots are sold. So that last 5 lots will be pure profit. Good luck!!