Hi All.
Yeh, anything over 12 really, but I personally don't like the 24 hour on scheme, at most I run 22/2, for cuttings, because I'm sure I've read that they metabolise slightly differently and make different chemicals/hormones/compounds under lights out, and in the natural habitat they never would get 24 hours light, so I like to give even cuttings a little "rest".
Under vegging I run 20/4 or 19/5.
Any flouro's will be OK, but I'd use 3 to 1 or 2 to 1 ratio of blue/cool/veg to red/warm/flower.
If your only doing a couple, those small 20 watters will be OK, but as they grow you will need more light.
Normal flourescent tubes will be OK too, get 3 or 4, 2 3 or 4 footers, and mount them to a board, or under a shelf, (much better if you can adjust hight easily though), you want them as close as posible.
I have one for cuttings, two cool tubes, one warm, 3 footers, mounted on a board, and this is fine for cuttings, and a few "bonsia" mothers.
Good luck.
See Ya
Martian