I would definitely not be resigning or mentioning it to his boss until he has the position. If he has to leave when on holidays that is the way it is unfortunately. He can always ring up and make a phone appt and resign over the phone to his boss while on holidays.
Agree with that! Do nothing until you have the offer in front of you!

They may get thru all of the above with two candidates and then choose... but as it is a a group intake, yeah it does sound pretty promising!! Good luck!