OK, so we're talking about dragging logs over 18 acres, and tilling not more than 5 acres or so. What are you going to do with the logs once you get them out of the woods - cutting them for firewood, loading them onto someone's truck, or simply putting them in one area so someone else can load them onto a truck with their own equipment?
I don't think you'll need a lot of hp for dragging logs and tilling a few acres. 30-35 would probably be fine. I would definitely recommend 4wd for dragging stuff through the woods and general ease of use. However, if you want a front end loader that can easily/safely lift those logs, you'll probably be looking at slightly bigger tractors - maybe the 40hp class or so. I would think a Kubota L4400, Deere 990, or similar from other manufacturers would be a good starting point if you're using FEL to lift the logs. If not, you could probably go a bit smaller, like an L3400, Deere 790, NH TC30, etc. If you do want to use the FEL for logs, you definitely want something with quick attach so you can use either pallet forks or a grapple bucket for lifting and moving them. The factory loader on the Kubota L4400 and L3400 does not have a quick attach option, but I believe you can get a Woods brand FEL for those that does. Not sure if the Deere 790/990 FELs have quick attach or not.
