Ideas for paludarium/riparium construction

[Gnomecatcher]

Okay, I have been doing a lot more planning than actually doing. My tank still resides at my parents place, but I'll be bringing it down to my apartment at school soon. I have an 18 x 18 x 18" rimless cube that I want to make into a sort of riparium/paludarium with a waterfall. I don't know how to go about it. I don't even know where to start.

If I were to use expanding foam, could I press driftwood and rocks into it? Instead of actually using the foam as fake rocks and wood, I'd use the foam to keep everything together.

Can I put the foam right onto the glass? I'm a little nervous about this; if I messed up or didn't like it, it would be a pain to take off. Is there any way I can build it outside of the tank first?

I have a 2" thick piece of reticulated foam that I was intending to use as a mattenfilter, but I've moved on from that idea. I was thinking I could cut it to size, build my expanding foam shelves for the plants and waterfall right onto it, and them affix it to the back somehow. Then I could cut holes into the foam for plants.