should be fine till your cham grows a bit, how old do you think it is?
and congrats on your cham and joining the forum, much knowledge is available here
I keep Zippy in one that size and he is 5 months now and still really tiny. The Panther babies were the same size as him when I saw them at the show, so I think it would be ok for a few months. Then when he moves inot a bigger viv you can put a new baby cham or even a crestie baby in the small viv! I also kept Monty in that size viv untl he was 4 or 5 months.
Another baby chameleon! Pygmy chameleons! Or some of those electric blue day geckos (the tiny, fast ones, can't remember the right name though). I think Laurie has some (or did have).
Yes, they can live together, but I don't know the answer to your other questions. I'm sure others on here will do though - I know 'Iwantone' is also in the UK and she breeds them.
Pygmies aren't terribly hard to look after. You only need substrate if you have females so they can lay eggs. If you use a clean up crew (like springtails and small isopods) then you hardly have to clean it (if at all.) I dont know about the prices over there, but here they are fairly inexpensive.