Don't see why you can't cut it back at least moderately now -- I whack away at mine whenever it threatens to depart the pergola and attack the house and it doesn't seem to have suffered. Haven't tried it but green wood cuttings should take relatively easily. The routine of stripping the first couple of leaves from the bottom of the cutting, dipping in rooting hormone, and then potting up in a damp medium will likely work. I'm sure that there are online descriptions of how to do it.