I've seen plexiglass mounts for routers on Amazon I think. Would I use something like that to mount it to the plywood?

Is a slot cutting bit different than what I would get using the mortise and tenon bits? I'm honestly confused about all the different bits. Mortise and tenon, rail and stile, and tongue and groove all look like they do essentially the same thing.

Here's the ones I was looking at: Rail and Stile Bits. My concern with those is if they're made for plywood or not, since 1/4" piece of plywood is not actually 1/4".