I'll make a video for C-stick buffering, Light press vs Hard press, and the option of Buffer vs Aid assist
http://www.youtube.com/watch?v=auuxj7hq0LA
Light Press vs Hard Press Air dodge
Light press: Only requires amount to trigger shield (just like L-cancelling)
Hard press: Requires press to reach the clicky sound
Attributes
Light Press:
+Easy on hands, longer playing experience
+Fast, more wave dashes are capable
+Control overall is better
Hard Press:
+
Very slightly more control in certain things
+Melee/Brawl people are use to it
+Fits in well with light shielding while light press air dodge slightly makes it a little weird
Buffer
Buffer replaces handicap in Wifi set [Reason being Laggy Wifi feels more like offline with a small amount of buffer, also playing with 1 frame of buffer even offline makes the game very awesome and enjoyable and feel amazing]
Crew mode replaces handicap in Full set and Aid assist is instead added which went over damage display (Which is a enforced 3 frame buffer for all players for people to get use to the game who are from Brawl, which in my opinion should be like the Wifi set and Crew mode should be ditched until added a different way that allows Buffer to use the handicap slot)
C-stick buffering
Use: In Melee if you were in shield hitlag (during the attack the game freezes both players) or shield hitstun (the attack hit and now you're stuck in shield based on the attack's damage) you could
Buffer (frame perfectly execute) a Jump/Roll/Spot dodge by holding the C-stick to perform the action as soon as you exit the shield hitstun instead of timing it yourself (possibly wasting extra frames in shield than you have to, making the difference of getting grabbed or not). Even Shield itself is a buffer-able move, since if you do an action (Like a smash attack) and then hold shield, you'll shield as soon as the attack ends.
Concerning P:M:
It's only available in the Full set, since it desyncs Wifi and replays just like the hard press air dodge. Thus the Wifi set doesn't have C-stick buffering nor Hard press air dodge (instead it has light press) due to both features (codes) desyncing replays (which thus also means it desyncs Wifi).