should I try to do it evenly like do 2 passes on 1 side flip over and do the same on the other side?Sure. You can thin anything. Just sharpen at an angle that's flatter than your cutting bevel and you are thinning.
should I do it with the ambidextrous method of switching hands or do it like I sharpen holding the knife in my dominant hand?
how do I know that I thinned enough?
how do I know if I didn't thin enough?
should I do the thinning with the 100/200 gritstone or the 800 gritstone?
asking all those questions because I have no experience thinning a knife