I have just set mine up and found it reasonably easy. Didn’t bother with kit as how much kit I take varies on the ride. Also sat down but only because it was easier and felt if stood up it would end up with too much sag as weight thrown to the front.
Looked at the fox tech centre and used the air pressure as a starting point then set sag from there.
Go ride, adjust if needed. I think you are putting too much thought into it.
Rebound was easy as well, just set to 6 and went a rode. Adjusted a little bit but only really notice a big difference if I move the dial more than 2 clicks either way.