No problem...
In flourescent tubes, wattage is determined by length.
Dont know if this is true or not - but would explain why I have had hard troubles finding higher wattage bulbs for the same length....
I would recommend AHSupply.com for a cheap DIY retrofit to get more plants.
Since you have a tube Fluorescent light, it will be difficult to change over to screw in Compact Fluorescent lights. HOWEVER, if you want to go this route, you can rip out the whole NO light setup and go to your local hw store and buy a swithched socket (get it in bulk - will be cheaper), power cord, power plug and light bulb. I did this to my 5.5G and is VERY easy to do. But...I dont think you will get enough spread of light doing it this way - the AH Supply way will be best for new lights.
You can not use incandescent bulbs. Well, you can - but wont be as effective and effecient as fluorescents - plus they user more power and create more heat.
Dont worry about the questions - best to learn first then do....
If your filter is not overpowerful - you should not have any problems with it sucking in blowind down plants. If it doesn - you can reduce the flow (which reduces ability to clean the tank but the plants will help a little in that department).
I like wenditii - I have yet been able to kill one of these - even in poor lit and poor taken care of tanks. In good tanks they develop MASSIVE root systems. When I redid my 30G, they were on the right side of the tank but had roots all the way to the left side of the tank. But that is in a HIGH light HIGH tech tank.
Good Luck
Aries