S is speed and SS is superspeed - not the same as superfree since some beans and pulses are superspeed foods but don't count as your 1/3 superfree on EE.
I think H and HH are foods with extra benefits to health, F and FF foods with high fibre and C and CC those with muchos calcium
If you go to the food diary at the top right hand side of the screen and then go to whatever type of day you are having, then click on the healthy extras tab and it will give you a list