Hi Judi,
I don't think the size of the tank is an issue for the RFA's. I was just snorkeling at a small island where they are almost a carpet on the hard bottom around the island. So being close together isn't an issue at all. Good flow and filtration will be important though.
By stock fluorescent bulbs, you mean the inexpensive kind that came with the tank? I'm not a big fan of them, but they should work. The colorful RFA's come from 30 to 60 feet deep and there isn't a lot of sunlight that penetrates that deep. They don't rely on photosynthesis as much as the less colorful, shallow water RFA's do. And because of that you will need to feed them regularly (like at least once a week, more often if you want them to reproduce). And consider a switch to leds as these guys look crazy cool under blue leds in the morning and evening. I even bought an inexpensive 2nd led fixture that is just blue and white leds just so I could run the blue channel. In the evenings when it's dark outside and the lights are off in the house, the all blue led lit tank looks like an old hippy poster under a blacklight! And the RFA's would do a bit better under leds (especially blue leds as that's all the light they get down at 30+ feet deep in the wild.