Hi, Jessica! Welcome to container peppers :-)
All of the varieties you mention will grow well in 5-gallon containers, although in your warm zone 9 location, you might consider going 7 - 10-gallons - the larger volume will hold moisture longer and also prevent the roots from becoming overheated. If the containers are too hot, you can move them into more shade or lean a board against the containers to block the sun.

I would separate the Jalapeno and the Habanero because the Jalapeno will outgrow the Hab very quickly. Cages will certainly support the plants better. Those small tomato cages are perfect for peppers.

Josh

i dont know why my zone is posting 9, it's actually 7 (I moved away from 9 a year and a half ago!), silly GardenWeb. Also, I don't know why I said habanero, I meant tabasco! lol

Either way, I will repot the jalapeno soon.

My plants are still very, very young. When should I cage them? When they get much bigger and I can tell which way they are growing or should I do it now?

You can cage them now or later.
I put the cages on early so that my cats don't flop down on my tiny seedlings, but as long as you cage them before you run the risk of damaging branches, they'll be fine.

Josh