By all means, buy a tractor. Get one with a bucket too, if you can. They are handy for all sorts of things all the time, especially when you're first starting. As for whether or not you need earthworks, you're the one who is there. Water is always good, I wouldn't cut your trees down to make a pond or whatever, though.
but I'm thinking of purchasing a small tractor with a backhoe(I know some people just say rent, but I'm the type of person that likes to pick away at things and not plan and having a tractor at my disposal will be more convenient.).