What does he sound like when he's playing?

Assuming that you like the sound he makes, you want to know how he does it. You might end up playing completely different music, and doing things differently from him, but it sounds as if you've got a rare chance here.

From what you've said get the impression that he's showing you how he does it, rather than laying down hard and fast rules that he expects you to bind yourself to. And when I ask him specific questions about how to do something, he never seems to understand the question. He always says either "Let nature teach you" or "Don't worry about that, just play the music."

One thing learning with him should underline - there isn't just one right way to play the fiddle.

Also, it sounds like he's teasing you a bit - I suspect that he knows that telling you not to bother about ever cleaning off the rosin might even seem a bit shocking to you. (All right rosin maybe messes the tone eventually - but there are some great fiddlers playing great music who never ever seem to bother about cleaning it off.)

Learning all he teaches you won't stop you learning other things from other people later. I think if you give up letting him teach you, you'll probably regret it.

And that l'Arche ceili should be a hoot!