Tank's looking good Butch! I've tried working with Tonga in the past and ended up removing all of it over time. It is really hard to work with. I somewhat liked my aquascape when it was mixed in, but it wasn't quite right.
Even when I google "Tonga Branch Aquascape" not too many attractive scales come up in an image search. It seems everyone struggles with Tonga.
As far as attaching the rock, go to HD and buy about $30 worth of regular old plumbers epoxy. Then use that to attach the rock, but first coat the epoxy in super glue gel to make it stick. The epoxy is malleable, but doesn't stick well without the glue. I've probably got about $40 worth of epoxy holding my scape together, but you have the luxury of doing it to dry rock rather than under water. Good luck!
By the way, hers are a couple of Tonga scapes I pulled from the web that I like. I really like the style of the second where they attached a bunch of Tonga to almost form a tree trunk that branches out. Then the tree "branches" sort of touch forming a cave, but not an ugly Tonga bridge.