how many hit points does a pavilion tent have?
How many would you like it to have?
How big a pavilion?
If it's just made of canvas it's probably got a hardness of 1 to slashing weapons. You probably wouldn't be able to damage it with a bashing weapon and a piercing weapon would make a hole in it just fine but wouldn't do any more damage to it (targets on the other side get full concealment and probably DR 2/- (one for the hardness, one for the hp done on the way through)). I'd probably give it X hit points per 5' if someone was trying to destroy the whole thing and say that in order to make a good sized rent in it would require X to be done. Maybe 5? That way a scimitar wielding fighter would have a good chance of slicing a hole in the tent with one stylish move, but might fail.
I guess question 2 is how many hit points does an expedition pavilion have?
Well, if you're in the realm of destroying magic items I think there are probably rules for that. But I guess a magic tent isn't THAT much more difficult to destroy than a normal one unless that's the magic. Destroying the thing while people are inside it could have catastrophic consequences for the since they're in an extra-dimensional space. Or they might just end up standing in a field a bit closer together than is really comfortable with a damp sheet of canvas hanging over them.
Core rulebook, page 175.
Cloth has a hardness of 0, and 2hp per inch of thickness. I doubt the walls are a full inch thick, so 1 hp/section. Walls are usually treated as having those hitpoint in every 5 foot x 5 foot section (I believe. It may be 10x10). So every 5x5 section of tent has 1 hit point.
Bludgeoning weapons would be ineffective. Piercing could possibly do reduced damage (not that it matters in this case).
Being magical makes no difference - only magical armor, weapons, and shields get bonuses to hardness and hitpoints. (If you did treat all magic items like they were +1 weapons, then they would gain +2 hardness and +10 hit points.)