I love that concept and, it looks great.... Awesome job!
We all learn as we go, its all trial and, error! You came to the right place to learn proper dragon husbandry. All of us started out just as you have. Most pet store employees don't have a clue what it really takes to care for a dragon. Dragons are not a beginner reptile by any stretch of the imagination. So please don't take this the wrong way when I try and, help you through this. Together we will keep your dragon happy and, healthy!
Dragons see in full spectrum color with good UVA. Yellow or any other color light, distorts their vision (confuses them), you really need to get a bright white light for proper UVA. Good lighting is the key to good health.
You were most likely told by a pet store employee that that crushed walnut shell substrate was good for dragons. I hate to say this but it is very hazardous. Dragons tend to lick things when exploring and, that spacious viv has lots of room for that. Add that to when he eats his bug meals and, he is bound to ingest it. Crushed walnut shells have sharp pointed edges that can cut your buddies intestinal tract, it like most loose substrates can cause impaction as well. Impaction can cause paralysis and, death if not caught in time. It is also a breeding ground for bacteria. I always recommend rough textured tile, it is easier to keep clean and sanitize. Nonadhesive shelf paper, paper towels and, newsprint are also good ones to use.
Those green hammocks can do real harm to your dragon when they get their claws hung in them. Dragons panic and, start pulling and, yanking their feet to free them and, in the process tearing out claws, pulling off fingers, dislocating joints and, breaking bones. You can cover it with fleece or some other snag proof material.
I hope this helps you in your bearded dragon adventures!