Well, out of the four problems you brought up, there is only one that can be seen as even a slight problem in The Shelter, the organisation I referred to in my previous post.
1) One could take several new players under his guidance, then do nothing and wait for them to level to give him experience points.
New players are handed to teacher\'s by a person whose role is to supervise the students\' education, so there is no way for teachers to get \"greedy\".
More importantly, there is no reward for teachers who decide to help, other than knowing that they have done a good deed and contributed to the roleplaying in PS.

2) \"Distribution\" of players would be really messy. Problems would arise, such as differences in time zones.
This is the point I meant could be a slight problem, though I don\'t think it is anything we can\'t handle. We have teachers from different timezones that are all dedicated to the game and can find the time to be with their student-s.
3) No general level based advancement in Planeshift. So what should it be replaced with?
Even if there was a level based advancement system in PS, we wouldn\'t make use of it to decide whether a student is ready or not. The teaching is not about leveling (though students will get some RP:ed training in the skills of their choice).
Graduation will be reached when students show that they have aquired knowledge about the PS world, built up a character, and know how to behave OOC as well as IC. Roleplaying is the essence of the Shelter...
4) Chance that a good quality new player would fall into hands of not so high quality experienced one.
I wouldn\'t worry about that one.

Thanx for getting me thinking a little more about the time zones problem...