A/
For scene referred profiles yes. You can also use a linear scientific, without the roll off of the curve in highlights. They are not created by default for all cameras but you can copy one.
For profiling I recommand to use an optimal exposure as well as a uniform lighting as perfect as possible, a LCC, and a good chart as a colorcheckerSG. Lumariver can obtain "acceptable" results with the colorchecker 24.
B/
No.
Lumariver only need to know the values from C1 pipe before the application of the profile and before the contrast curve.
C
No.
D/
I mostly use a color fidelity workflow even for anything else than reproduction.
However it can sometimes be more complicated for retouching and requieres some very good knowledge about colors.