Nice tank choice. The larger tanks are so much easier to maintain than the little ones. I could never get the hang of maintaining those small tanks, and forget about planting them, there's just no room to work!
Anyway, I keep large, planted tanks. I use Aqua Clear filters, have for years. Good quality, easy to maintain, price is reasonable. Starting out, a couple of AC
50s placed at opposite ends of the tank would be plenty as long as you're willing to change half the tank water every week.
Two heaters placed next to the filters is a good arrangement. I'd say a couple of 150 watt heaters would be sufficient.
What about lighting. Lights would be good here. A 75 G is pretty wide, so you'll need a strip that will accomodate two bulbs. A couple of 48 inch, 40 watt, 6500 K
, T12s would give your tank good intensity and distribution and grow quite a few of the low to medium light plants. More than enough to fill a 75 G.
PM me anytime if you have some more questions. I'm never too busy to chat about planted tanks.