Okay, bit late here, but I'll throw in some of the more fun stuff for the moment.
First of all, the best mixup I've found so far is to jump in with j.C. You now have the option of falling down with a 2B for a low, or you can dash-cancel the j.C and do j.B. This has worked really well for me so far. If you hit the j.C while high up, you can either do another j.C after the dash or you'll have to wait a tiny bit before you throw out j.B, or you won't connect after landing.
It's a bit tricky to find a really good spot to land this properly, but after throw or if you have them pressed in the corner it works really well. Just watch out for shield-attempts on the j.C. Just bait that shit if it comes to that.
Also if you do this midscreen, there's a good chance it will not only be a mixup, but give you a crossup as well, since you'll dash past them but still hit with the j.B.
For FF, yes, it is indeed nice for baiting shields. This works quite well if you've been spamming j.C as much as you should be.
However, the best use ever for that one is after a throw. just get a throw in, and then superjump forward and cancel it immediately with 22. Depending on your timing, this can make you land on either side of you opponent, making it a great crossup and anti-crossup at once.
What else...
Abuse 5C into 5A whiff cancel. That gives you some good advantage and can often work as a frame trap. Try to mix this up with throws, because we've already established that you get all his best options off a throw.