Well that's a tough question. The ride isn't very reliable, so your best bet would be to have a 'plan B' - for example, if you're going specifically just for KK and not at all the rest of the park, then perhaps you want to call the park when you're still about 15 minutes away, and if it's closed just keep on driving to some of the shore points to make it worth the drive. Otherwise, enjoy what you can of the park, and just keep an eye on the tophat to see when it goes over. They *TRY* to have it open with the park, but from my personal experiences it's usually about an hour or so late to open due to testing.... although if you're goal is to get video, it doesn't have to be open - just running :)
As for closing? I don't know.. I generally can't stomach being at the park the entire day and find that I usually leave by 7 if not earlier, and swing by Dorney (or the Jersey Shore) to complete the day. As of when I leave (at 7) it's still open, unless it's been closed for the day due to mechanical reasons (7 for 7 in 2005 I never got on it :( and had to wait until this year... and even THEN barely missed it)
As always, YMMV, but if you happen to catch it on a good day, then great.. but don't expect anything and you can't be disappointed ;)
