If i have two characters at level 30 and one at level 10, when I next get experience will all of it go to the L10?

Also, if a character has XP penalties, does their 'missing' XP get given to other characters?

XP is always distributed evenly among all the party members. There is a sequential distribution however. Suppose you have 3 member then XP is divided as follows:
15XP = 5/5/5
14XP = 5/5/4
13XP = 5/4/4

If the first person has 20% XP penaltie 13XP will be distributed as 4/5/4.

say what

Angryguy - what exactly did you not understand about Shrikant's post? It's hard to clarify it if you just say 'say what'.

But I'll try. No, all the XP won't go to the level 10. All three characters will get the same XP.

The XP penalties are taken off after the XP has been shared out - so it is not given to anyone else. It just vanishes.

lets say you have 3 characters and you are given 1500 XP for a quest. The XP is divided evenlly amoung the 3 persons 500xp, 500xp and 500xp. So each one of the three het 500 XP.

If the first one is suposed to recive less experience for soem reason, lets say -20% (for multiclass penalty and such) he recive 500XP -20% (500 - (500/100*20) 100 = 400XP instead.

If later your group kills a big monster, and recive 1500 XP (we wish), and the first 2 characters are level 30, and the third character is level 10. The first two might be so high level they are not suposed to get any XP at all for killing such a "small/weak" monster, but they are still allocated their part. so all characters recive 500 XP each. Then the two first are to high level to recive XP from that creature, thus the 500XP is rediced to 0XP. The third character will recive XP like normal.

This is a slightlly simplified version, since i didnt take the scaling xp for various levels into play and such.