How do you set your drag ?
60% of line strength (eg. 12 # for 20 # test) ?
How do you measure it ? (Would a boga grip do?)

lol...I never measure. I set it and if I can pull line with a bit of difficulty no to much though I think it's ok. When I get a strike I adjust it as needed. Usually if the rod bends and there is no run out it's generally a small fish. If it takes like it should be an ok size.

That's all I do.....no science to it for me...

No technical methods, same as above.

same here...keep it simple...