Hi.
Welcome to roses! : ) Without knowing which roses you have it is tough to say if they can handle being left outside all winter. I lost 3 this past winter that I didn't move into my unheated shed, but I have several that do fine being left outdoors.

At this point, you may just have to cross your fingers and hope for the best. Or you could plant them in the fall w/ as much of the "root ball" as possible, water them very often and again hope for the best. If you have a place to plant them, I think I'd do that if i were you.

A beautiful, very cold tolerant rose that you could plant, and leave in the barrels all winter, is Sweet Chariot. It is very fragrant and disease resistant. It also hangs a bit which I think looks nice in a pot.

Yellow leaves could mean several things. Older leaves on some roses turn yellow, it could be a sign of too much, or too little water, or yellow might mean blackspot which is a fungal disease.

You might want to post pictures of your roses on the rose ID forum and you might be able to discover which roses you have and how hardy they are.

Good luck!

Here is a link that might be useful: Sweet Chariot - check out all the photos

http://forums2.gardenweb.com/forums/load/rosesant/msg0807162428321.html?16

Butterfly, try the above post for lots of ideas for cold protection. I'm in CA and can't advise you, but these people know their stuff.
la