Well no under-gravel filter. Those things are just terrible. 8/
You could look into sponge filters. I've heard wonderful things about them for betta tanks, though I've never used one myself.
While it has a bit of a stronger flow and may need a little extra baffling depending on what you do with the tank/what bettas you have in it, I've always really liked Aqueon HOB filters. I've had great experiences with them.
As far as bulbs and wattage goes, that would depend on if you're going with life plants or not. For my artificially planted 10, I just picked up a pair of normal 15 watt bulbs from Petco....though in my five gallon I have one of those florescent long/strip bulbs and I like the look of it better.
If you're thinking NPT, I'm not sure exactly what to recommend as all of my tanks are artificially planted, but the Planted Tank section here has some awesome info about all that.
For substrate....well it depends. For an NPT, I think most people use some sort of soil topped with sand or gravel. If you're not doing NPT, its pretty much up to what you like. Personally I like the look of sand, but if you prefer the look of gravel then go with gravel.
For backgrounds, thats all about what you like the look of. I personally find those store-sold backdrops to be a little too busy....I prefer the look of a simple black backdrop, if anything. But its all up to what you like the look of.
For decor and planting.....again, thats all up to you. NPTs with some driftwood pieces are great if you can do them, lots of benefits, and they look pretty awesome. If you want to go artificial, I'd suggest silk instead of plastic.....and of course they sell all kinds of different caves and decorations and whatnot. Its all up to your personal tastes.