I've had slugs in pots. I don't know if they damage roses (someone else will probably tell you about that), but if you're worried about them you can sprinkle Sluggo or another safe slug killer around the plant. Careful, though--not all slug killers are equal. Some are quite dangerous to pets, etc.

I agree that Sluggo is the best and safest I've tried -- it only kills snails, does not harm the soil and will not harm humans or pets.

Yes, snails & slugs eat roses. Actually, snails & slugs eat almost anything if it is a plant, or if it's dead animal tissue. Most of them (with the exception of the few that are predators) are about as generalist as general feeders can get!