My TC30 is a 4WD HST model, so I can't reference the 2WD gear model too well. Given what you stated you will be using it for, the 2WD gear model seems adequate, however 4WD actually puts more useable HP to the ground and will actually be better for use with the tiller when you get it. I noticed your question about the FEL, if you are considering one then 4WD is almost a must. You can use one with 2WD but it's use will be quite limited.
You should buy as much tractor as you can afford, don't limited yourself by only considering short term usage. Once you have one you will find a lot more that you want to do with it, and will only be frustrated if the tractor doesn't have the capability to do it. The TC30 is a very capable, economical, and reliable tractor. I have just over 100 Hrs on mine, and am quite satisfied with it. There have only been a few occasions when I wished that I had bought a bigger tractor (I have 7.5 acres), and none where I had wished I had gone the other way.
As far as tires go, it depends on the surface you are working. If you are only doing plowing or mowing in weedy and really wet areas ag tires will do fine, but they will destroy nicer areas like lawns. Turf tires do well on a lawn, but are almost useless (my opinion) when it comes to plowing and working in mud. The best compromise I have found are the R4 (industrial tires), as they have a less aggressive tread than the ag tires, but offer more traction in wet/loamy areas than the turf tires.
There are a LOT of very satisfied TC30 owners on this board. Do a search and you'll find quite a bit of useful information.
Hope this helps,
Kevin