I live in MD so I'm not that familiar with CA species. Based on how common the various CA tree frogs are, I think it may be a Pacific tree frog. Here's a site with a lot of photos of them:
http://www.californiaherps.com/frogs/pages/p.regilla.htmlThe Pacific tree frog has that stripe on the face that your baby does while the other common CA species, the California tree frog, does not. That seems like a great web site that should help you out.
Frogs often have slight color variations. Normally with newly morphed frogs, it's not related to their sex (only when mature). It could just be natural variation.
Tree frogs only come to water to breed. So, if you release the babies, they will probably head for the trees and climb. When breeding, tree frogs can be loud. That web site has a recording of their call.
It's up to you if you want to take Smartie and his pals back where he came from or release him at your place, as long as they're not too far apart in location.