Thanks for your help John, I realise that they are going to require a lot of setting up/attention, and that's why im being a pain in the *** here with the questions :P

Despite the difficulties, I'm still interested in keeping dart frogs, and I'm looking into the best ways to feed them at the moment. dartfrog.co.uk seems to have a lot of good stuff, and I'm going to check if any shops nearby carry food for darts in case of emergencies. I think I will buy a tank on Monday (away this weekend), and start setting it up. If the humidity and temperatures seem fine then I'll start looking at where to buy the frogs!

At the moment, i'm interested in "custodian" invertebrates for the substrate, are they a worthwhile addition? Is it common to use them?

Oh, and I just wanted to say what a nice site this is, full of friendly people with a passion for frogs, awesome!