I wouldn’t attempt to cool tubes, not even a fan. They are quite happy little munchkins just sittin there being hot. What is the "good sense" to cooling them? Don’t.
Anything else may re-distribute the heat unevenly.’ Those rings I’ve sometimes seen? Wow, what??
If they are heating up excessively (no, I’m not sure what that means, either - I’ve seen some running white hot, and that’s extreme with the volume on 11, but within design tolerances, sort of), chuck out your amp and get one which is designed properly.
As for vibration - microphonics. Big topic. Some types of tubes are prone to that, and I’m not sure if there is an easy answer.