If the terrain is driveable in the thickets, a brushhog would probably work on those. I drive right into them slowly(creeper gear) with the loader low forcing the debris and brush down. I also sometimes raise and lower the loader to crush the brush and small trees. Then I drive right over it. The main purpose of the loader basket is as a curb feeler, looking for stumps and debris that I don't want to go thru the brushhog. Anything up to about 3" dia I push down and drive over and let the hog shred it. You have to be aware of your surroundings though, as it can sometimes spit out some pretty large chunks of wood. You also need to prep the tractor for this type work, by covering and securing any loose hoses and wiring under the tractor.
Another method is using a fork bucket on the tractor. I have one I built with eleven 30" tines tines spaced about 6" apart. I run this low down to the ground, with the tines parallel to the ground. As I move forward, the tines slip thru the lower brush and start to rip it out. the debris builds up on the forks and eventually I lift and back out with a bucket full of vegitation and debris and go dump it on a pile for later combustion. This has the advantage of ripping a lot of the brush out roots and all. Grapples are also andy when you start finding downed branches and such.
Doing stumps with a loader is going to get old, real fast. I think a ripper shank on the
3PH is better for stumps up to 4"-6". I can usually rip on either side and then rip into the rootwad and lift with the
3PH to pop them out. IMO, if you have more than 10 or so 12" or better stumps, either clear around them and hire out their grinding or removal, or get a backhoe.
Oh, and I am doing what you describe on 7.5 acres with stumps up to 30" using a 28HP 4WD tractor with backhoe, brushhog, forkbucket and ripper/subsoiler. If you are starting out small, I would stat with the fork bucket. For me, that has been about the biggest bang for the buck clearing brush.
Good Luck