Ask-a-Dave's-Gardener: Sally Holmes bushes, 1 by NewRose

NewRose wrote:
Hi everyone, I am very new in gardening and need some help with pruning roses.
Here\'s my story: Our family moved into a house in Lilburn, Ga about 3 years ago. We have a large yard with tons of flower trees and shrubs. I don\'t have green thumbs and I am not confident when it comes to taking care of plants. I discovered just now three Sally Holmes bushes on the side of our house. I am not sure how long they have been there. The house was built in 1986. The roots are as big as my arm. One of them had a vine that grew straight from the root and intertwined with the rose branches. I removed the vines and cut down tons of dead twigs and branches. However, I am scared of cutting too much. I noticed the bushes bloomed more flowers after I removed dead branches but not as much as the pictures I see online. Sally Holmes rose bushes should give hundreds or even thousands of blooms but mine only got a bout 40-50 blooms each bush. I figure I need to be aggressive in pruning but don\'t know how and where to cut. The bushes grew to be 12 feet tall and top branches don\'t produce any blooms. I read online these are bush/vines so the branches grow out really long and falls down when they get heavy with flowers.
My questions are:
1. Should I prune heavily, cutting down 5 feet of the top branches and 1/3 or all branches around once blooms are over? Or wait until next spring?
2. I don\'t know if there are any suckers since I don\'t know how to identify them, should I just cut away any new grow from root?
3. If I want them to grow as vines, how do I put up a fence or post for them to grow on?

I love the flowers and wish to keep them around with lots of flowers to enjoy. Any input is appreciated!!