That's great that Chewy and Jilly are getting along! Sometimes I wish I had an indoor-born bunny, but Floppsy makes up for it!

That's wonderful that you're getting Jilly a playmate as well! I was thinking the same thing as Heather, make sure if you're getting one, that they are spayed/neutered. Bunnies can get along grea together, but make sure they are never left alone, at least while they are getting used to each other.(I have learned that mistake before )
As for the size/dominance thing, I wouldn't be sure. The only time I had two bunnies and they were indoor-born, one was at least three years older than the other, and they got along pretty well, but I can't say that will happen with all buns.
If you're looking for a good rescue place, why not try www.petfinder.com, if you haven't already. You can search for the type of bun you want, and in your area, and see how many buns you can find. I found plenty of rabbits in my area, but all in-door born. But anyway, hope it works for you, good luck on the new bun!