Hello,
I just built a 4x2x2 viv in the style and quality I believe your talking about. I recently built this..and am still finishing...
I used birch to make a face frame and I used 3/4 in cabinet grade plywood (if you can afford it) or for the sides and top I used like birch or maple 3/4 ply from home depot. I got several small cans of stain, and tested the colors on a scrap of the ply I used on the sides, and on the birch. You will easily come to a color you like, this is where you say how dark and how warm do you want it? apply one or two coats max and let it dry. Then apply 3 to 4 polyurethane coats to the whole carcass once assembled to seal everything. You want to have completed wood cutting and building, and have sanded the entire thing. Apply a coat of polyurethane once a day for the next 4 days.. then let it cure for a couple more days, to get the smell out. That will seal the wood and then it will easily tolerate the heat...