You won't lose them. You're in a zone where you may be able to grow them all year, depending on your winter. Cannas continually produce new stalks which will bloom even tho old stalks may be exhausted. Here, we cut the cannas down when a frost kills the foliage, which was just in the last week or two. Do you get frost? I wouldn't cut the foliage until the last possible minute. It will continue to absorb energy for the rhizomes. Throughout the season, as old stalks finish blooming (each stalk may have two or three flushes of blooms), you can trim down the old stalks so new stalks can take in nutrients and sunlight. You can cut the stalks to about an inch tall. Don't worry, you're not going to hurt the cannas. In fact, in your zone, they may be "weeds" for you someday. Believe me, if I haven't killed them here in zone 7, with my neglect, they're safe with you. LOL

I whack my type IIIs off at six inches because I prefer new growth up from the ground rather than from last years vines but most won't cut that severely. It is up to you. You can start at the ground and go up to the closest set of buds and cut just above them.

Well, if it's happy with your temperature range, and it's a California native, it's most likely Salvia leucophylla. If that's the case, then it's probably a good idea to tip it now so that the coming shrub is good and branched. S. leucophylla often grows over 5 feet tall in as many years, but the Point Sal variety tends to remain about 3 feet by 3 feet. I recommend either a pretty big, draining pot or to put it in the ground.

The advice you read in rose books to prune back roses to encourage growth is more relevant for hybrid teas to encourage show-type blooms and not at all necessary even for them. You can prune any rose to try to encourage it to grow into a pleasing symmetrical shape once it gets big enough, and certainly deadheading (cutting or pinching off dead blooms behind the flowers) or a periodic haircut of the outermost couple of inches of branches (if you're lazy like me) can jumpstart a rose into increasing or continuing the blooms, but it's totally not necessary. In our cold zones, some people don't realize that Knockouts can lose branches to winterkill as much as any other rose, so you have to prune out the dead wood or they look unsightly pretty quickly. I spring prune all 75 Knockouts at my church every year now after they posted a pitiful note a few years ago that their "no care" roses looked awful. All they needed was the dead wood taken out, but that is all they need yearly and they bloom more or less all season, though you can see the dead blooms after a while and they slow down as they have more dead than live blooms. I'm just not willing to commit to deadheading or edge trimming all season for that many roses not in my own yard, and they do fine. Bottom line is I'd let them grow and do their own thing, particularly in zone 7, unless you enjoy the puttering about with roses. Cynthia