Honestly, no, there's nothing you can really do about it other than either mash the key or play with very low spell queuing time. I wouldn't really suggest the latter, since you'll end up having tiny holes in your rotation all around, but it is an option.
As to cancelling Ebonbolts, unknown. There is likely a point if you catch it fast enough it'd be worth doing since a cancelled cast will reset the GCD spent, but I'm unsure of the specifics of that point. I'll see if I can get a real answer regarding that in the next few weeks.