starting to build a viv

Finally starting to build a new viv for Hiei. I've never done this before, so forgive me if any of these questions seem stupid. We got blondewood made of birch for the walls. It was cabinet/bookcase quality and 1/2 in thick. The plan is to use a combo of screws and wood glue to keep it together. The wood is already bought, so here's hoping there's nothing wrong with using blondewood birch, I couldn't find anything bad about it for animal cages.
I'm planning on staining it, then using minwax quickdry polyurethane on the inside to protect it from poop and such. Is there any difference between the quick drying stuff and the not quick drying stuff? I've looked around this forum and people just say use polyurethane sealant, but I haven't seen any specific brands or types listed.
Also someone said polyurethane takes weeks to cure. I've never used polyurethane on its own before. The last time I stained something I just got minwax stain and sealant in one, painted it, left it on the porch overnight and by morning it was fine to use. What is curing? How do I know if it's done and the viv is safe to use, because I'm assuming it's not until it has.

Well, I found out about curing. I'm hoping to start staining and painting this weekend, but I'm still not sure about the different types of polyurethane so if anyone knows, or can let me know the brand/type they used, that would be awesome.
Before we start building I'm trying to get the vents and plan where they're going to be. I'm wanting to put 4 of the small circle vents along the back and two rectangular vents along the sides, one at the top on one side and one on the bottom on the other. The viv will face a heating/ac vent, so my thought was to put the vent on that side on the bottom to keep any drafts from getting in.
I'm having a hard time finding the small round vents in any colour but white, though. I was hoping to find them in black since all the furniture in that room has black hardware. Has anyone seen them in black? If so where??

You may be able to paint the vents, I'm not sure. I might use Polycrylic instead of Polyurethane as it's water based.

I need to make it waterproof because sometimes Hiei has water in his poop if he eats a lot of hornworms or veggies and fruits with a lot of water. I didn't think polyacrylic was as water resistant as polyurethane.

I like polyurethane better; polycrylic, at least in my experience, is not nearly as durable against water. Curing is the process by which the various components of the polyurethane link up to form a solid surface. The solvents used to keep it liquid "off gas" during this time and that is what the fumes are. The final product is pretty safe but the solvents and incurred stuff is pretty nasty. Remember also, a bit of furniture in a room is still different from the box your pet will need to live in, you won't be able to keep the air fresh and Hiei would be stuck breathing the fumes of its not fully cure. You will need to let it cure in a well ventilated area - part of the chemical process of curing rely on oxygen so fresh air is important. UV light can help to so leaving outside in the sun if possible may help things go faster but it can still take 2-4weeks.

Polycrylic will probably be fine if you use some sort of barrier on the floor. If you use tiles you can put shelf liner below them. Polycrylic is not UV stable - areas exposed to the uv light will discolor differently than shaded areas. It cures in 48 hours or so.

If you can get an epoxy sealer like for ponds those are no toxic when cured and the most durable. Also the most expensive.

Your vents will also give cross flow of air, the low ones should be on the cool side the high ones on the warm side. Sorry not sure if they come in black.

I was planning on letting it cure on my back porch until it was finished. His current tank is a bit small, but I think it'll be okay until the bigger viv is ready. I have a picnic table I can set it on while it cures outside. I didn't know the sun would help it cure faster. I think I'll try to put it out in the yard on the table when it's not supposed to rain.

Thank you for the advice on the vents. I didn't realize it would make a difference. I'll make sure when I set it up the hot side is the one with the vent up high and the cool side is the one with the vent low.

I'll discuss the advantages and disadvantages of the polycrylic with mom, since she's helping me build it and it's going in her living room.