Thanks for the help. I didn't realize that you could rent tractors. Who rents them. Any idea how much they rent for?
Pricing for rentals is going to be dependent on location. In my area you can rent a Kubota MX5100HST for about 300 a day/800 a week.(Plus delivery and the box blade)
Questions:
Is it a proper two lane road or a single track drive?
What is your "lean" budget?
As for the other points:
Loader-definitely get one with the tractor, or at least make sure it has the valve and mounting for later.
HST or Gear-Personal preference and skill levels would determine the correct route. HST is dead simple, and a lot less hassle for loader work, but gears free up more power and don't have the high pitched whine of the HST, and are less stressing when doing long runs.
4X4-Yes. For several reasons. Resale values of 2wd versions are much lower, you can get away with a smaller tractor, it helps with braking with a load in the bucket.
Belly Mowers and Bush hogs-Those are two vastly different things. Having one of each wouldn't be bad, if you had a need. I'm guessing you meant "rear finish mower" instead.(Correct me if I'm wrong) Only smaller tractors will have belly mowers. Anything with a 3 point and PTO can run a rear finish mower. Get a good used commercial zero turn instead. You'll mow faster and reduce the compression on the yard from taking a heavy tractor across it. I have an ExMark Lazer. It's a 1996(I think) and still works great.
Wet or dry clutch-Whatever floats your boat. Tractors are made to work. If a dry clutch was weak they wouldn't get used, because nobody would buy them. Wet might be nice to have, but is by no means a necessity.
Horsepower and weight-This is the primary question. There are people like 5030 who have a lot of power and can't imagine doing the job with much less. Then there are people who have a 20ish HP SCUT like a Kubota BX or Massey GC and find them perfectly sized to almost any task. There's no rule that says X feet of drive needs Y HP.
You'll either end up power limited or traction limited depending on the HP/Weight ratio you end up with(and specific circumstances). I'd rather be power limited, since it just bogs the tractor down. Being traction limited is hard on the terrain, since spinning tires can really mess up a lawn, or dig a new hole. As for specifics for you, without knowing your ballpark budget, the amount of time you have to work on the road, and the other tasks you have for the tractor, hard to say. Some people, myself included, got the largest tractor they could afford. The reason I did that is that anything smaller would be inefficient for my tasks, and I'd rather spend more money than time. Others would disagree with that.
Basically, we need more details in order to give you more specific answers.