The event's probably going to be all about the watch and none about the rest.
Yeah, I read that after the fact. I'd still give it an outside chance that they announce Broadwell MBP's but if Apple Watch is the star of the show, then that's somewhat unlikely.
I believe that you can return it within 2 weeks with no questions asked.
What happened to your 2011 MBP? If it was graphics card related, Apple just launched a repair program:
Battery is shot and the whole system has been slowing way down. It finally refused to boot this past weekend for a few hours. It's non-retina, non-SSD so I'm not sad about getting a new one. The new one is screamingly fast and wonderful. I just don't want to buy it a month before Broadwell MBPs roll off the production lines and then already have obsolete hardware.