The ends combo events I included to simulate the "10 second" or w/e duration you have to continue the combo. E.g. True Thrust puts up a TT combo buff for Vorpal to use to gain the combo bonus. The TT "combo buff" ends in 10s (or w/e the time is). Not really useful for a normal scenario, but maybe for fringe simulation cases at some point, or to simulate someone failing to press the correct button (e.g. they press TT -> FT, skipping Vorpal).

Jumps take longer than the OGCD. Hard to say by exactly how much. I'd guesstimate roughly 0.5 seconds of delay on the next GCD. So a total of 1.5-2.0s. It does also depends on which ability you animated before using the jump though. There seems to be a pretty good variance in attacks, with DE/CT/PH being the fastest, FT/TT being decently fast, and VP/ID/HT being consistently slow.