Couple comments. I think 25-30hp is about right, at least as the point to start your search. I wouldn't go too big as bigger tractors will cost more, damage turf more, and aren't needed for finish mowing unless you want a huge mower. 25hp may not sound like much, but the diesel engined tractors get a lot more work out of their hp than the gas riding mowers - we have a 20hp gas riding mower and a 50hp utility, and the utility doesn't do 2.5x as much work as the riding mower, it does more like 20x as much work.
Turf tires will do the least damage to turf... BUT.... do not have much traction. I don't think you would be happy using them with a loader for any dirt work like digging, pushing piles around, pushing into piles you've already made, etc. I can have traction issues with R1's (rears loaded) and MFWD doing loader work! I think R4 tires are likely to be a good bet for you as long as you don't go on your grass when the soil is saturated. (The tire debate is endless, you can find literally dozens of threads on this topic...)
MFWD or 4 wheel drive is not very important for mowing, but useful for loader and dirt work. Most CUTs in the size range I'm suggesting will have MFWD, but it may not be all that important for your tasks.
Where is your property? Will you be mowing weekly? I know I hate mowing on hot days, and the debris kicked up by a big mower is significant. I also have some allergies which mowing is terrible for - to the extent I've tried mowing with a dust mask on, but haven't found that to work very well. I would seriously consider a cab if I did it over again, despite the big added cost. In the 25-30hp size range there are only a few cab options, but it may be worth looking into if money isn't an issue.