Sony a7s II Picture Profile and Grading Basic Questions

[George Paul]

I am new to the Sony a7s II.  I bought it to film in 4K in coral reef ecosystems.  White balance is difficult underwater, and I am grappling with that issue.   I am new to all this.  

Any recommendations on picture profiles?  I have been advised to film in "log" so that I can do a more sophisticated job in the color correction, or grading, in the future.

Assuming use of a picture profile, how does one get from its flat appearance, to something that looks bright and colorful, like a tropical coral reef underwater?  Must you use a LUT, and if so, where to get them?  And don't you have to get a LUT that is specific for a picture profile?  Or not?  I have been scouring the Internet and am surprised by how little guidance there is about this topic.  It seems esoteric, at least to me.  For example, assume I don't want to use a LUT, but instead do all the grading and color correction in Premiere Pro's Lumetri workspace.  Where on earth would I be able to read on how to do that?  How to skip over the "Basic correction" LUT operation and do things yourself?

Many thanks,  

George Paul