For the bigger trees, it depends on how many you have and what you expect the end result to be. If you want the stumps completely removed, you'll need a backhoe. If you have many (subjective, but I would think >20), I'd hire it out or get a true backhoe as Slackdaddy has suggested and then sell it after you're done for something smaller. If you only have a few, but still want the stumps completely out, it let's you justify (sorta) a backhoe attachment for a CUT. If you go this route, get a heavy tractor with good hydraulics.
For the underbrush, you can use a bush hog and grind it all up. This assumes you can easily gain access safely with a bush hog, and the brush is not bigger than 2 or 3 inches in diameter. It'll be hard on the bush hog though.
The other option for the brush is to use a loader with a tooth bar and/or a grapple. You can scrape the ground with the digging bar, pulling the small stuff out of the ground as you go. You'll be left with big piles of brush to dispose of. Then either burn it or shred it.
I have similar property and have been doing the same thing. Though, I only had to remove 5 or 6 stumps. I chose a Kioti CK25 for its weight and hydraulics. I used the digging bar method to gather up under growth and then ran it through my
PTO shredder attachment. I couldn't really work a bush hog in there very effectively, and wouldn't have needed it after finishing. So, I went the chipper/shredder route because I always have trimmings that need to be shredded anyway. Burning would have been hazardous because I couldn't easily get the pile to a place that was safe to burn. Also, I can only burn certain months of the year.
In the Kioti line, the CK20 is probably a better size for 2 acres. But, I decided to forgo the HST and step up to the CK25 gear for about the same money. What swayed me was the weight difference and the hydraulics of the 25 vs. the 20. I could also get a larger backhoe, which I did.
If you plan to use your tractor to mow a lot, you might want to think about a lighter tractor that you can add weight to. Whatever you do, don't buy too small.