I echo what Crazie.eddie said about the python and about the canister filter. With light stocking, your current filter is fine, but if you're going to have large fish, a canister filter is definitely the way to go--something to ask for next christmas or your birthday at least.
You have a number of options regarding your substrate, and the substrate message board has tons of information about possibilities. I would say, though, that flourite is a lot sharper than eco-complete. Eco is "rough" but not particularly sharp. Your inert gravel on top will save you money initially, but you may regret it in the long term. Consider root-tabs as well if you end up with heavy root feeders like swords, lotuses, etc. especially if half your gravel will be inert.
I have not looked into the canister filters at all yet. Is this something that may be added in the future, or is it something I should plan to install at the begining?
Also, I used the "substrate" calculater for eco-complete, it generated 175 lbs to put a 3" substrate of eco in my tank... even at the least expensive LFS I found it in it's @$23 for 20 lbs. (gulp) And they only had about 4 bags (80 lbs) in the sales display.
The math scares me sometimes...
Fortunately, I have time. Absolutely nothing will get set up until after Jan 28th - I'm leaving town again for 10 days.