Go with two 50w heaters. Neither is strong enough to boil your tank should it fail "on" and you have a backup should one fail "off".
AHsupply is an excellent source for lighting. I got their 2x13w retrofit for my 15w hood. It took me a couple of hours to change my 15w normal fluo. hood to a 2x13w PC (power compact) hood, and for cheaper than any other source of PC lighting that I've seen.
A successful planted tank is more beautiful than an equally successful unplanted one, IMO. However, there are some added considerations for live plants that can complicate your life a little. But that needn't be a deterrent, like all other facets of aquaria, if you plan ahead and do your research in advance, the you stack the odds in your favour.
If you go unplanted then you need very little gravel. Just enough to cover the bottom. If you go planted then you need a little more; 2-3" thick will make anchoring the plants easier than a thin layer.
edit: Oh yeah, skip the carbon. Save the insert for a "rainy day", like when you go on vacation or for just after medication to remove trace amounts of meds. For day to day tank operation carbon just isn't necessary, a good maintenance rootine will do better for you.