A 3ft tank should be fine for a Saulosi specific tank! I'd suggest something along the lines of around 15 (3 males/12 females). These numbers are not exact but anything from 12-15 should be good. I would also suggest at least 3 males (or more if desired). If you only have two males, the dominate male will bully the other one. Having at least 3 males will help spread the aggression. Hope this helps :thumb:
I don't think it's too much light, but I'm not a pro when it comes to lighting (I just have the standard lighting in my tank) the only time I would think to worry about lighting is when you start thinking about adding real plants. I myself don't have any real plants so I can't help ya out too much with the lighting issues or questions. Check out these 3ft Saulosi Colony tanks, hopefully this will give you an idea on how cool it can really look!
Lighting doesn't really matter in a mbuna tank, though I've found that PCs can be a little bright for their liking (currently using PCs on my 3' until I'm able to get some new bulbs for my other ballasts - my demasoni don't seem to like the extra light).
You don't really need a sump for a 3' tank, either. Your filters/pumps should ideally turn the water over 10x/hour.