The best thing you can do for your new trees is to mulch them. Apply a 3- or 4-inch layer of organic mulch (like wood chips). Keep it a few inches away from the trunk, and extend the mulch ring clear out to the dripline if possible. (The dripline is the farthest reach of the branch tips.) Have you ever seen those mounded piles of mulch at the base of trees? In the industry, we call those tree volcanoes or mulch volcanoes and they're a big no-no.
No fertilizer is necessary right away unless you are concerned about soil fertility. If you've done a soil test or think your soil is particularly poor, a balanced fertilizer (10-10-10 or 12-12-12, for example) is a good idea.
Don't prune your trees unless it's just to remove suckers near the trunk. The trees will use every bit of leaf surface they have to support the growth and establishment of their root systems.
It sounds like you're on track with the watering. They'll need a deep soak every 10-14 days, so set your hose on a slow trickle or water with a trickling 5-gallon bucket or a Tree Gator.