Should iris be pruned back each year to encourage growth?
Pruning is not really the word to use. You aren't really encouraging new growth. If the plants are healthy, they will grow on their own. Generally you might need to trim the fans a bit to neaten the area. A lot depends on the temperatures and moisture conditions.
I live a lot farther north than you and my winters will often have lots of snow on the ground for extended periods. Or not, like 2 years ago. I cut back my iris to so that I can see where to clean up the stuff around the soil. If you don't do that, then all kinds of bad things might happen (fungus and iris borers). It just makes it look neater and it is easier to pick out dead stuff.
If you don't, you will learn for next year. Experiment a bit as I have done. Do part of them one way and the rest a different way. Next year, you will see which one works better. Iris are tough plants and ultimately you will have more than you thought you would.
Bearded leaves gradually die on their own after the mother rhizome has bloomed and made babies.
I pull off outer leaves that have turned brown but only trim if replanting and I don't want the plant to tip over.
As Jim said, pruning does not apply to irises. Once you cut a leaf in half it does not re-grow itself. (no branches to prune)