I can answer the rest of the questions, Chris.
The two story is how I have done all of mine... I have a shelf running almost full length in each of my 4 enclosures.
Yes a cabinet below would make an excellent storage area.. With ventilation, you can also store your live food containers.
With the one enclosure that is sliding doors, yes I do have some small difficulty cleaning... Normally I remove those doors, and spot clean as needed, deep clean once a month with rubbing alcohol. I do the glass with vinegar.
Wellllll for a new dragon, in a new enclosure, all glass should be covered until dragon becomes accustomed to their new environment. All of mine are wood top, 3 sides and bottom. I have ceramic tile on the floor ( don't seal those in, you'll find being able to remove them for cleaning to be much better.)
The decoration thing is personal.. however we do "borrow" ideas from others... Some make their own decor too!
Hinge hands down... lol
Now substrate, that's kinda tricky. With young dragons, it is much better and easier to clean with a solid substrate... It also cuts down on the chances of particulate substrate being eaten, and causing possible blockages. It also cuts down on dust in the air the animal breathes.
You'll want enough to bring the basking temps to 105-120*F. You'll also want to position the UVB tube close enough so the dragon benefits from both on their basking site.
As for the uvb, go with a 10% tube. If you are in the UK, I would suggest the Arcadia 12%. Remember to change out those tubes every 4-6 months.
Oh that's a good question... I think practice, study, and just doing would be that answer... The longer you work at being a reptile keeper/owner, the more you learn... And you never learn enough... Wonderful opportunities to study.
All of my enclosures are indeed rectangular.. 4' long, 2' wide, and the tallness varies. I would recommend at least 18" but the sky and your ceiling is the limit...
Oh yes... Digital thermometers are Great ! They give much more accurate reading then the analog type... Also, temp guns give accuracy in less time and you can easily "shoot" a temperature anywhere... Remember to take that sort of reading within 2" of your target.
Ventilation... That depends on your location, house ambient temperature. I live in southern Ga, and my house can get pretty warm in summer... I have ventilation top, and sides. Some of us have holes in the back and the sides... It all depends...
I built all of mine... I like them, but the more I build, the more I explore different aspects. The doors, the walls, the shelves..
With a finish, you'll want to use Min wax polyurethane. At least 2 coats.. allow to fully dry (cure) for 48 hours. That said, you'll want to reapply that finish annually or there about as the finish can deteriorate under high temperatures.
I hope this helps you ! Good Luck !
Thanks alot for your help as you probably guessed by the earlier post I don't have much experience with retiles my mate owns bearded dragons and thats where the idea came from...I think tbh I need all the help I can get cause this project is turning out to be a nightmare to research :/