WD: Sorry, got a 2. Yes, I'm going to keep the Grace/Health aspect. The 2 points get added to your Grace, and add any Con modifiers to Health, +1 for the new level.
Strawhat: Okay. To bring Psion into line with Pathfinder rules, make the following changes: d6 hit die, Class skills: Acrobatics, Autohypnosis, Craft (any), Heal, Knowledge (any), Profession (any), Psicraft*.
*Psicraft includes Concentration for Psionic abilities, same as Spellcraft does for normal magic. At the moment, all other aspects of psionics remains as per 3.5.
Character creation is addressed in the first post but, briefly, 4th level character, 25 point buy (+1 for fourth level). Hit points are divided into Health (equal to Con, plus Con modifers for each level, plus 1 for each level) and Grace (the class hit die, maximum for first, you can roll on Invis Castle or get me to roll the remaining 3).
Pathfinder skills and skill calculation method, Pathfinder feats - you'll have 1st, 3rd and human bonus. I'm not using the favoured class aspect of PF, nor do you get the additional +2 ability score (to bring you in line with the others who didn't either).
I'll sort out money/equipment later, but the characters are somewhat poor and underequipped compared to standard levels.