Can bugambilia grow in Texas (Dallas area)?
This is native to subtropical locations and hardy in Zones 9-11. Southern parts of Texas are quite ideal for this plant. While your area is Zone 8a, as long as the proper winter protection is given, I think it should be fine. You could also grow it in a container.
Do bugambilias react well to rejuvenation pruning? When should it be done? How long will it take to grow back to 5 ft. ?
So you mean bouganvillea?
The following might be helpful: http://gardeningsolutions.ifas.ufl.edu/giam/plants_and_grasses/flowering_plants/pruning_bougainvillea.html