Is this case compatible with Tanos systainers? Also, can I use this with a Festool vac?

Yes, Makita's interlocking cases use the same connecting system as Tanos/Festool's Classic Systainers so they are compatible with one another.The dust nozzle is optional and sold separately, link below. The inside diameter of the dust nozzle is 1-1/4". We can verify compatibility with the Festool 27mm hose when we open in the morning and update you with that information.https://www.toolnut.com/makita-195559-1-dust-nozzle-fixed-base.html