I'll help narrow down some of these (btw, keep'em coming. makes me think about things I didn't consider).
1. definitely want some water more for attracting animals than using it as potable water.
2. this will primarily be for hunting and recreational long distance shooting. So game activity/presence is primary objective.
3. no payments here. we have allocated a specific fund for this so it will NOT exceed that nor will we be making payments.
4. need to look more into the tax exemption status.
Since you are wanting this for hunting, think about it this way. If you are going to have 3 hunters using the property with each wanting to kill a buck, you will need a high deer population. Hill Country type numbers of deer and game. If you buy a place that has a deer to 10 acres then you will only have 10 deer on 100 acres. If you have a 2.5 doe to 1 buck ratio, you will only have 3 bucks on the property. What is around you and how they hunt is going to greatly effect what you have on the place as far as game.
Another key point will be Antler Restrictions-AR's. They can be of benefit to deer numbers in some areas and in other be a detriment.
I will also say I am not a fan of road or highway frontage on a hunting place. I prefer just a gate on the highway or road at most if at all possible. Poaching is something I would ask the local Game Warden about in any county I was looking to buy in. Ask about theft issues also. Nothing worse than buying or leasing a place only to have someone steal your cameras, feeders, or break in to your camp repeatedly.