Some people use loaders for snow removal on pretty big drives. I don't find them great myself and wouldn't want to be without a blade or blower. Well, I wouldn't want to be without a loader for stacking the stuff either. My choice was a 3ph blower.
Can't help much with specifics for bucket size or weight. However, you might want to keep it light if a main use is mowing turf on fairly level ground. Wheel weights are hard to change, filled tires are impossible, and extra weight doesn't do turf any good. You might want to hang loose until you see how much weight is required to get the traction you need. Just be aware of the safety issues (you can read them in the archives). Upsetting your new tractor could be a lot more than just upsetting.