My SLX cranks keep coming lose on the ND side. I might as well upgrade while I’m at. I was looking at the M8000 cranks do I need a special chainring for these cranks or can I get away with my current n/w ring?

New ring. To be honest the idea that its an upgrade is a bit misleading I would say. I would have the SLX over XT M8000 if buying a pair of cranks.

Ah that’s a bit crap.

Will a 11 speed ring run with a 10 speed chain?

Yup.

asymmetric bolt circle on M8000, a few companies do them as well as shimano though. I was running a superstar one on mine, now got a 30T shimano one x 10sp 11-42 sunrace cassette, slx shifter and m8000 rear mech, works perfectly