I would recommend looking for a large tank on craigslist or your local classifieds. Sometimes you can find a 90gal tank or larger for the same price as a new 40gal. Pinto is right - if you start small, you'll need to buy multiple setups. The rule of thumb for RES is 10 gallons of tank for 1 inch of shell. Since an adult male can be 7-9 inches, and a female can be 10-12 inches, you're looking at a very minimum tank size of about 75.
For filters, canister filters are definitely the best. You'll want a filter rated for about 3x your tank size. (So for a 50 gallon tank, you'd want a filter that's rated for at least a 150 gallon.) Many members here use the Rena XP3/4. I've got a Fluval 404 and FX5 which I'm very pleased with.
No matter what tank size you get to start (even if you get a 40 gal) I would recommend getting an XP3 (or equivalent) filter, so when you upgrade the tank again you don't have to buy a new filter.
For lighting, there have been a few reports of the 10.0 being too strong and causing eye problems. I think most people use a 5.0.
You'll want to mimic the daylight cycle, so about 12 hours on and 12 hours off (give or take).
As Nathan said, the main site (redearslider.com) is one of the most accurate RES sites out there.
Once you've browsed through the main site, you can post any more questions you have
