Any good fish shop should have canopy tops available and I agree that buying is much less expensive then making one.

I have creeping fig in with my Leus along with lemon button ferns. Your design is nice and just keep in mind that you want to not take up a ton of the back wall so you have room for the Bromeliads.

As for Springtails, I buy a starter culture from Joshsfrogs and watch his video on using the culture. Its a starter culture so you have to get the culture going and then add them to the tank. You will want to culture your own fruit flies though. It is so easy and once you have done it a few times in only takes a few minutes to mix up a new set of cultures.

I buy Joshsfrogs and black Jungle fly media and excelsior since both are easy to use and both produce a ton of flies.

Not sure if I gave you this link but here is the build for my Leus in a 20 long tank.
http://www.frogforum.net/vivarium-te...pic-heavy.html