I'm a big fan of bran myself, I put down several inches, but you have to make sure everything in the enclosure is firmly on the bottom before you add bran, otehrwise your beardie could dig underneath it and get squished. Same goes for other substrates, but washed playsand isn't usually as deep or as fluffy and diggable.
Climbing structures - personally, I have sand-blasted wood branches mounted on rock bases for him to climb on, flat rock piles, store bought half-logs to hide under and fake plants. All the branches I use I strip the bark from, sand off any rough spots so they are completely smooth, and bake in the oven for half an hour to an hour at low temps to kill anything living in them. I prefer fake plants, because I know he's not going to eat them, and they aren't going to hurt them, and if they get knocked over or dug out, I dont' care I just put them back in place. Real plants are a ton of work, no matter what you put in there they have to be edible, he's going to try them! I wouldn't use cacti either, your beardie will at some point jump on it, and get a nasty injury.
I'd suggest doing a search on google.ca for bearded dragon, tons of good sites come up and many of them have great photos of habitat and good ideas too.