Congratulations on the new rig!
I've never used slide toppers, and never had a leak. If you park under a lot of trees, you might need to sweep the roof of the slide before running it back in. Some folks don't like toppers because they make noise in the wind. And they aren't cheap.
A 2000 watt Honda will power all of your electrical outlets and items such as a TV, etc. It will most likely run your microwave too as long as you aren't pulling a lot of current from other devices. It may or may not run your AC. Most likely not. If you just want it for charging your batteries, consider getting a good solar charging system and save the purchase price of the generator. BTW, the lights in the trailer run off of the batteries, so the generator isn't needed for the lights other than to keep the batteries charged.