I just had two 30 amp circuit put in for my grow. It was the best thing I have done thus far. I would occationaly blow a breaker (is that the term) when I was using the 15amp circuit. I would be fine untill I was a really hot day and the AC would kick on and toss another 600 watts. Then all hell would break loose. Havent blown one yet since the change.
But yes 15amp would be fine for what you have. Although I would suggest using a 20 amp or better yet using 2 separet 15 amp circuits, one for the lights and one for the other crap you have up there.