Re: "san", vs. "sama"
I've lived in Kitakyushu, Japan for over 11 years now. I've taught pre-school kids and up. In my experience san is used for most situations. When being extremely polite, one can use sama as in shops, okyaku-sama or customer. When politely referring to another's wife or husband, goshujin-sama or oku-sama is used. Within your circle, you may drop the sama. And yes God/gods, kami-sama.
For really young kids, chan and kun are mostly used. Elementary school, too. But using san is not improper. For the most part, chan is used for females and kun for males, but BOTH can be used for the opposite sex. Something similar to Margaret being referred to as Marge, Maggie, Meg, Peg or Peggy. From junior high onward, girls all but lose the chan from teachers. Your circle may vary.
My wife has always called me Eddie sensei. She is a teacher, too. My friends call me Eddie-san. My aikido sensei and most dojo members call me Eddie-kun. And at 41years of age, it's nice to be thought of as a young'n.