ACES Exposure "node" and Sony HG

Hey,

I had a long weekend of shooting some test footage, cameras include Varicam 35, Alexa XST, Amira, Alexa Mini, Red Dragon, Sony fs7/F5/F55.

I have 3 main questions:
1. I have set up an ACEScc project and allocated the propped IDT's to all cameras and color gamma, BUT some of the stuff is shot in sony's "Custom" mode which is not a full Slog and has a Rec709 mapping, should I use Camera709 IDT? the footage still comes out flat if I put it side by side with Slog3 that has an Sony Slog3 ITD.
2. Why is there no Slog3Cine option in IDT's?
3. In Nuke or Baselight I can dial in exact exposure values, so I can take a node and put in to bring the exposure down by 2 stops and the will be mathematically correct, in my test I have many shots over and under exposed to show advantages and problems with over or under exposure in different cameras and formats.
Is there a way to get a clear numeric exposure node in resolve?

Would be happy to share test results as soon as I get it all lined up.