SP will not decrease when you sit (dance, pose, etc.) .
If your SP is lower than the max SP, running around is better than just standing and waiting for the SP restore. (especialy with Penguin)
For Chameleon Trickster: in PvP try attackin the opponent with "Quick Strike" skills right when the battle starts. This will gain you a lot of SP.
If you want to start over without loosing your items, just put all the equipment in your treasure chest. Delete the character and make a new one with the same class and name. Your new character can use the old equipment even if the item says it's used. That means if you don't have Reskill or Restats drug, you could do this to rebuild your character. (But your level is back to 1)