I used to play something on the Master System, for which I know quite a bit about Japanese Mahjong. I know some of the special hands, like buried treasure, 13 orphans, 9 gates etc. The Dora, is quite useful in Japanese Mahjong, and that is what I go for, if I have 2 tiles that match the showing tile in the wall.
Yes, Riichi is used in Japanese Mahjong, and I think it either doubles your value or adds another point to your score. I've rarely played Riichi, because I usually get Pungs/Kongs to help my hand quite a bit.