There are so many things about this tank that make me nervous, prime among them being those weird seams that are so open and then filled with silicone. A glass tank is supposed to be made of glass, with a thin silicone bead acting as an adhesive between panels. This tank is more like a bunch of glass walls interspersed with a bunch of silicone walls! An exaggeration, to be sure, but I think you know what I mean.
But...if it can be made to work it will be a terrific showpiece! And you seem to be going at it the right way: slowly, carefully, methodically and with forethought. I am keeping all my fingers and toes crossed for you!
Sounds like the lighting you have planned will be great for an open top tank with lots of emergent plants. Perhaps some terrestrials with their roots in a pot/container of some kind placed right in the middle of the tank? A big piece of gnarled driftwood extending up out of the water?
Really looking forward to watching this progress further.