Gnats don't usually eat leaves, they feed off fungus in the soil, so keep on the lookout for other bugs. They may be a bit too small to see with the naked eye, so might want to get a magnifying glass.
As far as auto water systems, I'd suggest a simply DIY setup, using a 5-gal bucket as a res for the nutes, and a simple aquarium pump hooked up to a drip feed line. You just need to be sure that you have the correct adapters to connect the drip line to the pump. You could look for a drip kit that connects to a garden hose type connection, and then make sure whatever pump you get has that same adapter, which is pretty common. You'll also want to think about how you plan to deal with the runoff. Most common thing to do is to build a short flood table a foot or two off the floor for the plants to sit on, then make a drain on the table into a bucket. There are many ways to go about it. Do a bit of research online, but make you think everything through a few times before you get too far.