I made the same jump as you did - came from a Golf I and a Jetta III to these little lovelies. Very similar cars, really. You won't see anything unfamiliar except maybe the engine orientation.
Carpet really isn't that easy - it's deeply molded with thick foam padding attached to it. The only spot I'd really like to see under the carpet that severe rust can hide, is under the carpet is on the firewall and at the bottom of the a-pillars. You should be able to peek under the passenger side carpet without taking anything apart. If I can't get my head in there, I'll just hold a phone out and snap random pics until I get what I'd like to see. Pedals are in the way on the driver's side and you can't pull the speaker & grille because there is another electrical component under there. You can see a bit of the lower a-pillar through the front door openings, but not enough to be 100% sure.
Also look for any signs of rust staining near the lower corners of the windscreen seal. In addition to the commonly-corroded license marker lights, turn signal mounting flanges, battery tray and tool pocket...check the upper pinch welds at the trunk hinges.