When I send out a Wipe command, do I need to uninstall the VPP apps first? My concern is that if I wipe , I'll lose the licenses to the apps I've paid for, or does the wipe automatically strip the licensing and put the licensing back into my VPP?
The licenses actually stay assigned to the device in whatever way you have them scoped. They'll be available for reinstall once you've finished setting it up again.
If you delete a device record, the licenses get recycled back into the pool for re-allocation.