I like Laura's advice for filtration, but nothing wrong what so ever with the Fluval 405. I use one on a 72 gallon and its more than adequate.
Another CO2 vendor is www.sumoregulator.com
I almost always reccomend for new comers to start off low tech, but give yourself some room with your purchases to advance to high tech in the future if you so desire. Don't limit purchases based on the notion that you only need "100 WPG" (btw, I hate that rule, but Laura clearly gave you a good breakdown of wattage options based on fixture selection). Nothing wrong with buying a fixture that has alot of light, but only utilizing part of it (for instance, purchasing a dual ballast PCF fixture that has 260 watts of lighting, but only using 130 watts at a time). This would allow you the versatility later to upgrade if you want. Of course, this can be budget restrictive, but trust me, you are better off buying big now, then cutting corners from the start only to have to upgrade later. But this is ONLY MY OPINION
. Take it for what its worth. This is an addictive hobby.
A full pressurized CO2 system will run you about 200 bucks if you shop well (that includes a tank). You can skimp a bit here and there, but I never reccomend it. Buy quality, you get quality.
Eco complete is an excellent starter substrate.
Gravel heater is not necessary.