I haven't found any white paper for D-log M color profile and how to expose it correctly. First of all, is there any reference for IRE of 90% white or 18% middle gray for that profile? Or at least if we should shoot 0.0 EV or overexpose (for example +0.7 EV). Secondly, what is the preferred base ISO for best dynamic range? I assume for normal Rec.709 profile it's ISO 50, however usually for Log profiles the base ISO is much higher. Any guidelines?

It's not real log so no need to overexpose it.  I actually underexpose it by -.3 EV.

And how about base ISO for D-log M?

I find 0.0 in D-log M tend to slightly over exposed seeing i. Lumetry scope.
I would say -0.3 under expose.