Two quick questions..

[Bodah]

First question is: Are the bonus hit points that an ooze gets depending on its size a one time bonus only?

Second question is: When you roll a critical against a creature that is immune to critical hits is the entire thing cancelled? What I mean is, when the creature is immune you dont auto hit it and you dont do x2 damage with the critical? Or is it you still auto hit it but you dont to the x2 damage?

 

[Destil]

Bonus hit points for oozes are indeed a one time deal.

I think you're confusing two related (but seperate) rules:

a) On a threat (a natural die roll of the weapon's threat range that is also a successfull attack roll) you make a confirmation roll, if sucessfull you deal more damage, depending on the crit multiplier.

b) A natural 20 always hits.

Creatures imune to crits ignore a. B still applies, always hitting on a 20 is not a part of a critical hit (though it's always a threat itself), it is a seperate rule.

 

[Hypersmurf]

Ooh, what about Vorpal, Energy Bursts, and the Mace of Smiting?

-Hyp.

 

[Darklone]

Ooh, what about Vorpal, Energy Bursts, and the Mace of Smiting?

You forgot the Eagle Claw attack against constructs.