100 watts per square foot or per plant will work fine. And I even vegged one plant for 3 months in a five gallon bucket, using just 107 watts CFL. It grew and branched out really well. In my case I was only using a 1' x 2' area and the walls were flat white, so a lot of light bounced back onto the plant for an extra boost. Since your grow area is about 2-3 times as big as mine, I would think doubling your lights would be a smart move. I got away with 107, but really I was pushing it and there is no question I would have got better results with more light. Growing wise, it did the trick. Just don't expect your plant to win any cannabis cup awards.
Oh and how many plants? Depends on the pot side. I'd go with 3 gallon if you want decent size plants. 5 gallon if you want it to grow as big as its genetics will allow. Really, it's going to grow in any size container you give it, but bigger pot equals bigger plant. You can also start small and transplant to a bigger pot. However, this will delay it's growth a little. I've transplanted one plant five times and it did fine. You almost have to try to kill them. lol.