As so often seems to be the case, I'll have to agree with TripleR here, and the other recommendations also. If you have 13 or so hillside acres of down trees, it's going to be one monumental undertaking getting it cleared up. I'd get a forester or the county extension agent to give it a look before making too many detailed plans. Seems to me it's critical to determine if you have any salvageable timber, because that will dictate whether a logger would clear it for the recoverable timber, at one extreme, or whether you'd have to pay a logger entirely out of your own pocket for his work, at the other. Sorry to say, I think paying fully to have it cleared is going to be an expensive proposition.
Seems to me that attempting to clear the land entirely on your own as an initial priority has its own set of issues. You have such a combination of risk factors involved: hilly property, down and leaning trees amid standing timber, novice tractor operator, novice tree cutter, unknown backup and support crew, etc. If you can do it in incremental stages, so you acquire experience and skill over time, it's do-able, but it will take you a long time to both learn and use what you've learned.
Regarding tractor size, others have reflected wisely that you'll need something larger than a 30 hp tractor if you're going to clear it yourself. You also may want to consider a second machine, such as a used, full sized backhoe, for your land clearing, to be sold when the heavy work is finished.
Regarding the comment about tractors having a narrow stance. It's an issue of tractors needing ground clearance to operate on rough ground, unlike, say, a go-kart, which has essentially no ground clearance. With the weight of a tractor up comparatively high off the ground, it doesn't take much of a pothole, dip, stump or other unexpected obstacle to throw a tractor over sideways on a slope. So running tractors around hillsides pulling logs and such has danger written all over it.
We are going to be doing some hillside tree clearing this fall, so I have a lot of sympathy for what you're getting into. Our project is quite a bit smaller than what you've staked out, but it will be a challenge nonetheless, and we expect to be working at it ourselves over the fall and winter months. We added a 3 point tractor logging winch to our implements so we can pull the trees off the slopes from level ground.
All the best with your plans. Be safe and enjoy the experience. I hope the advice you get here on TBN helps get you on the road to success.
