Welcome to the world of Planted Tanks!
Your lighting setup is a little on the strong side, here is what I would do: run two of the bulbs to start with, until you have a established tank full of plants without algae problems, then add the third bulb, and if everything is cool you can add number four, although that would be a lot of light for a tank that's only 12 inches deep.
You will need CO2, filter sounds just fine, I would not recommend a substrate heater, get one of the neat inline Hydors that you can connect to your filter, IMO a great solution.
1/2in of gravel is a little on the thin side, I would recommend more like 2-3 inches, with a thin layer of peat (if you must) and some laterite in the lower area. If you want the best, there are substrates that are thought to be used in planted tanks, like Eco-complete and Flourite (do a search on the board), but they are quite a bit more expensive compared to gravel.
You will need plant nutrients: Macros and Micros. Read through the articles section of this site, that should give you plenty info to get started in the right tracks!