Some of the older frames were made of Poplar wood, lightweight, straight grained, strong, and easy to work with. Some were made with Maple, some with White Oak. I think it just depended on what the shop had on hand at the time the order came in.
Yes it does matter. As some woods age they warp. Some woods are oily and who knows what that would do to your negs. Plywood is always an option but other woods just plain look good.
You can make a camera out of plywood and it would serve our purposes but people don't.