Ring flash syncing?

Can anyone link me to a good beginners article on ring flash use, especially syncing? I am confused about TTL, e-TTL, i-TTL, slave and manual controls, etc.

I am also wondering if you can use ring flashes from one manufacturer (say Canon MR14EX) on another manufacturer's equipment (Lumix GF1, µ4/3 format)

Thanks
kww