Replant the bushes as if they new. Water in well when you replant, and cover the bush with a mound of soil or mulch to at least 8 to 12 inches. After 3 to 4 weeks, after the roots have settle in, you can remove the mound. If you are dealing with a rootball, there is no need to cover the replanted bush with a mound, but I like to prune the bush back down below the active growth. The bush will then wait until the roots settle in before it kicks back into active growth, pushing out new shoots from the dormant eyes.
Some people start with the garden framework, finishing paths, lawns, etc before working on the beds.
With a rose garden, you'll be moving lots of materials, plants, and equipment around the yard. You'll probably change your mind about a few beds before you're done. Although I would lay out the garden structure in the first stages, I would wait until I finish with the mucking about before I added the finishing touches. And you won't have to worry about damaging that birdbath, wrought iron trellis, bench, statue. Now you can add the finishing treatments grass, mulches, paths.