Personally, I would try and do a dry start if you want a carpet in a 75, should be a relatively simple thing to get going.
For substrate, I would get organic potting mix of some sort and use that as your base, probably enough to fill about the bottom 2-3" of the tank at the very least, up to you if you want to use more. Then, I would cap the soil with either pool filter sand (cheapest option), or some sort of small grain gravel. Depends on what you want for the color and all that jazz.
For lighting, I do like the catalina fixture that I have, its the 4 bulb t5ho with 8 led moonlights. I run 2 bulbs during my cycle, and then have the other 2 running on a burst effect in the midday.
Filtration, I do like my ehiem 2217's. They are reliable and have a ton of filtration. I have two on my 75, but I would go with as many as you deem fit. However, regardless of filtration, you will most likely need more flow in your tank. For that, I would recomend a koralia unit, I use the 750 personally, but I would ask around which model would be best for the plants and fish you plan on having.
I can't help you with co2, since I Haven't figured that out yet. I would recommend though that you get scissors, fishing line, hairnets, a really damn good pair of tweezers, and a thing to measure out our ferts for when you start adding them.
Good bit of advice as well, I would recommend that you plan out the kind of plants you want, their placement, and the fish you want well in advance. You don't nee to be set in stone, but at least have a few general ideas.