Hi Patrick,
Sorry for the delay in response, I've been out of town for the past week. I had someone try the v2.5.15 drivers in my absence. I spoke to one of them briefly and he mentioned that the drivers were compiled and loaded, but there was no difference in behavior. However, it's unclear whether or not we need VF-specific drivers.
Special note on #3: we allow kvm to auto-generate a MAC for the VF interfaces. This works well with other guests. Is there a reason why auto-assignment could cause issues for FreeBSD? Just curious.