My three Rams can be quite vicious at times and it's only due to the fact that I have a large tank that they don't end up hurting one another. I'd stick with three or, at a push, four. Watch out if they pair off though. Fireworks will happen and a 33g wont be big enough for even three. Mind you, I have yet to see a female Rame on sale! Make sure that you get decent quality fish too. Many are too inbred and are stunted and/or mis-shapen. You've got to keep the water in top quality condition for them to flourish and even then they have a tendancy to drop dead for no particular reason. Make sure there are plenty of hiding places and plants (one of mine has made its home in a dense patch of Vallis).
My Rams tend to like vegetable foods more than live insect type foods. They love peas! Saying that I have seen them eat newly hatched brine shrimp and fry. They only ever chase the tetras for fun. They wont eat that size of fish.
My adviswe would be to keep as few as you can. They will pay you back by being fitter, healthier specimens.
WK