You can certainly see a launch from the "regular" parts of KSC. The difference between the VIP areas and regular areas is that you have a view of the rocket on the launch pad from the VIP. Granted, it's miles away and looks very, very, very small. You won't be able to see the rocket launch from the main Visitor Center until it clears the tree line. Typically, they set up a huge screen at the Visitor Center with audible launch commentary. So, you get the close-up on the screen and the actual rocket a few seconds after liftoff.
It's tough to say if a 6:30pm launch will be supported. Technically, 6:30pm is just the start of the launch window. If that window is short, they might stay open. If it stretches for multiple hours, they might not.
You may want to try contacting Kennedy Space Center. Over the years, I've found them pretty responsive to questions:
https://www.kennedyspacecenter.com/info/contact-us
Sadly, I can't advise as to the difference between viewing a launch from KSC or Orlando. I've had tickets for multiple Space Shuttle and rocket launches. Each time, I missed seeing the launch. When I was at KSC, each attempt was scrubbed. The one time it wasn't, I got into a minor car accident that made my car undriveable so I missed out.
That is something to consider: There is a high possibility that you'll go and the launch will get delayed. It's rocket science, which is pretty complex!
I have seen both Space Shuttle and rocket launches from Orlando. To maximize the chances of seeing something, you need to be listening/watching launch commentary on your cell phone. If you're not, it's a frustrating experience because the launch might not happen at the beginning of the launch window. Also, it's very tough for tourists to know exactly which way to look.
Hope some of that helps.