I'm going to just parrot most of what mproteau just said.
You're able to cut anything from the TLX lines, propmaster lines and swiftsenics line. Pretty much anything in the Vault doesn't have GSD/Studio files for them.
Making adjustments to 3/16th would be relatively simple, you'd just move the score line slightly to make it work. That being said, as mproteau has pointed out, the slight angling of the bottoms is a non-issue, and likely not worth the hassle. (Not that I can claim to have tried)
Here is a picture of which I had a bunch of stuff cut sitting beside (and on) my laptop for a project I was doing. You can see how they come out.
The nice thing is since the perforated edges for fold lines are so perfect, you can see all that glue then cutout parts on the walls and posts are skipped giving you near perfect results everytime. For me this makes the investment worthwhile since when I was first starting cardstock modelling my stuff turned out terrible due to my inability to cut/score straight lines even with a ruler
Cutting the templates out for the foamcore is not even worth the effort, I use a slide cutter and cut around the outside edges then spray adhesive mine to the board. I use regular paper for my templates, not cardstock.
