Well, my first word of advice is to DO YOUR RESEARCH!!! It's undoubtedly the
single most important part of being able to maintain a feasible vivarium while keeping both your flora and fauna happy. Check out the forums around the internet about different vivaria, including the following sites:
www.dendroboard.com
www.blackjungle.com
www.vivariumforums.com
www.amphibiancare.com
www.thechocohut.com
I can't say that I know of any really good insect forums- you'll have to look for those yourself.
As for your water section, stay away from goldfish. They're messy, big, and don't tolerate the tropical temperatures necessary to maintain the vivarium very well. Again, make certain that you do lots of research. Depending upon the size of the water section, you can decide between a vast array of aquatic flora and fauna. You need to provide us with some more information before we can be very helpful.
Be careful that your millipedes and cockroaches don't bother the other inhabitants (if you're going to include amphibians.) Hylids are largely nocturnal, so a hungry cockroach could easily take a bite out of an amphibian's sensitive skin while he's sleeping. It's hard to mix various animal and insect species because the dynamic of their interactions and various behaviours. Now, seeing that you have a rather enormous vivarium at your disposal, you may be able to overcome some of these issues, but do so at your own risk (and that of the creatures under your care.)
Well, if you provide us with a little more info, I'll be able to help you better. Until then, do lots of research, and keep us posted. Good luck!!