If you're going to set up CO2, you don't need to dose Excel. The best way to dose nutrients is via root tabs - liquids aren't as effective (won't get to root feeders well), and get expensive.
If you're willing to deal with the potential mess, go with a dirted tank - your plants (especially the carpeting ones) will thank you. Miracle Gro Organic Choice Potting Mix is a crowd favorite (alot of people will emphasize MIX and not SOIL here, but the more reading I do, the more it seems to be a non-issue). You'll want to cap it with something, sand being an excellent choice. Also, look into mineralized top soil... Mineralizing isn't necessary when using MGOCPM, but it helps.
Back to CO2... On a tank that big, DIY CO2 is going to be a real hassle to keep up with, and probably not very cost effective in the long run (sugar isn't CRAZY expensive, but you'll go through it quicker than you realize). A pressurized CO2 system is a big initial investment ($200-$300 for something basic), but cheap to maintain (tank fills are only $20ish bucks, and will last you months at a time). If you want your carpet plants to grow well, you're going to need CO2 in some form (Excel won't be enough).
Your lighting is probably good, yes. Your filter might be a bit much - people generally try to keep things in the 5x-10x turnover per hour range.