The light tool doesn't need or use vis; it's something that could be added at a later date if it became necessary though, but it would always be optional.
Beware that we're in semi-experimental mode with parts of this. Some things may change in coming weeks, but any changes will be optional, off by default, and auto-detected by the engine.
No md3 and unlikely to ever exist. There's no need for it and IQM is just so much better (faster too after today's work.

).