I've had up to 700Cx37 tires on my Randonee, although over the years I've gradually moved to 32s. It's a bit compromised on deep mud or 2" gravel, but I don't really enjoy riding either of those.

REI installed fenders on my daughter's bike for free when we bought bike + fenders. I'd expect the same for a rack. I did notice that the mechanics weren't any better at installing the fenders than I was, given the time it took for them to mount them. I wonder if they install more racks than fenders.