I really don't recommend that you start deep subsoiling to bring up more rocks. Your soil is likely solid rock with a bit of top soil so the more you deep plow, the more rocks you will have and you will never get them all up.
A landscape rake might work for windrowing up the larger surface rocks. The tines are about an inch apart so small stuff will sift thru. Grass will not go thru and will just stop everything up, so that may be a problem for you. A box blade will gather up rocks and topsoil and anything else it goes over. You may not want all your topsoil dug up although the scarifiers set at 6" deep might work to bring up some of the rocks that will naturally rise over time. I wouldn't go any deeper than that.
As for tractor size or brand, as long as you have an established dealer for the tractor brand, you likely wont have any issues. Almost all the CUTs build are reliable but just like automobiles, one is occasionally a lemon, but you shouldn't let some web poster that got one and now badmouths every XXXXX brand as being bad sway your thinking too much.
I don't think I would be looking at any SCUT for your work, not even for mowing. A 25-40 HP CUT would work well, having plenty of lift capacity, weight and power to dig out rocks and lift and carry them away. You can check the specs on just about any tractor made at Tractordata.com