As for 3 will being effective, I think this could be changed by having either
cryostasis be resisted by fortitude or
premeditation having a low will requirement (it's strange that it doesn't actually).
Will affecting psi points won't do much unless 3 will puts you below 50 psi, and even then, there's neurology. It's a step in the right direction sure, I'm just saying it's not going to stop 3 will being the most effective secondary will for any attribute intense builds.
Incidentally, as far as psi regeneration, I've thought about it and if one really wants to make psi boosters useful I think regeneratino would have to be something like:
Psi regen = max (0,(Will - 9 )*4)
So you only start with any regen at all if you're a full on psiker, and it's pitiful, requiring psi boosters in the beginning. This is fine for psi secondaries, or focused psionics with some other tools like grenadier, as a psi booster and default psi makes for well over 150 psi points even with some nerfed max psi. "pure" psionics would have to go full bore into Will, which I think is fair considering how wtf awesome psi is; and even going full will would require boosters, and full psi gear would be a godsens (beetle/head/neurology)