Good suggestions. The only thing I would add would be to also get a set (front and rear) of aftermarket bumpers from RPM or T-Bone Racing. The bumpers on all the RTRs I've ever seen are purely cosmetic, or may as well be. A good bumper set is going to save you from breakage. If you're going to be running around trees or other pole-like objects, putting crash barriers around them will save your butt, too. My track is laid out around several trees. My buddy and I took blue sleeping pad foam and cut them lengthwise into 8-10in strips and put them around the base of the trees, then put small safety cones between the tree and the foam. Saved us many times.

2wd is as simple as it gets, and easy to maintain. 4wd of course has a few more bits of hardware to make those front wheels turn, so you'll have two more differentials (total 3) to maintain, but 4wd is easier to drive than 2wd and is more capable over rough terrain. 2wd will teach you to drive better as it requires more skill.

Try to buy your RTR without the included battery and charger, as they are usually crap anyway and only add to the cost. Also, don't be too surprised when the steering servo craps out. It's one of the items the makers tend to cheap-out on to keep the cost down. It's the most common part that fails first on all RTRs. Just replace it with a $30 Hitec when it does.