Six months later I'll answer my own questions...
No, there isn't a Getaway spinnaker kit, but there may be soon.
Yes, you can--and I did--modify an H16 spinnaker kit for the Getaway.
See my recent post elsewhere in this forum for details, and check out my web page for photos and more details.
No, you probably can't install a zipper in the Getaway's main.
A reefable version of the Getaway's (boomless) mainsail would be problematic. I researched and pondered this quite a bit--I wanted to try to install a zipper similar to the system used on the Wave & Trifoiler sails--but ultimately my sailmaker and I decided not to attempt it. The reason has mainly to do with the cut of the Getaway's main: it has a large roach and a curved foot. If you were to make a horizontal cut and remove a section from the bottom of the sail, the foot of the reduced sail would be significantly longer than the tack-clew distance of the original sail. This would totally throw off your sheeting angle, not allowing you to control the flatness and twist of the "reefed" sail.
Yes, you can use the Wave's zippered main for a reefing option.
Since the Wave's main is more triangular in shape, the zipper-reefing method works well; sheeting angle isn't significantly affected by removing a bottom panel. It also turns out that the foot length of the Wave main is only slightly shorter than the Getaway main's tack-clew distance. I went ahead and bought one and, with the use of pendants to extend the halyard (and allow use of the halyard locking hook), it works well. Check out my web page for photos and more details.
Only happy when tinkering and spending money,