There's nothing wrong with a bowsling. Everyone uses it in Olympic archery. It does eliminate the death-grip on the bow, which is likely to introduce tension in your bow-arm, and potential variation in your shot.

I found it interesting to see what archers were using - mostly some variation of finger sling, over wrist-sling.

I noticed one of the Koreans tucked his fingers up, so that no finger was wrapped around the bow at all - evades the temptation to grip entirely.

I'd tend to agree with you - pick one anchor to teach beginners. There's no ideal one - just choose one. I don't think there's a correct order to teach them, though some people think a hunter/barebow anchor is 'easier'. I can't say I've noticed.

Barging in on someone else's lessons is just plain bad manners, IMO.