Wow, long thread for one day.
I am a fan of the Oxford comma, and double space after my periods. It's just the right thing to do.
I know a lot of ESL people in my work, and get a lot in the classes I teach. My second favorite feedback ever from a student was:
"He correct my grammar all time, but his grammar not good"
Just to be clear, I didn't correct her speaking grammar but her written lab reports where grammar mattered. Hilarious. I suggested she should go to the school's writing center where she could get writing help for free. She didn't listen.