When you apply for, transfer or modify your ARC in any way, remember to insist that the police double-check the validity of your re-entry visa. If there are any problems, ask for it to be replaced while you are there.
I say this because the police 'forget' about this, and while you have an ARC allowing you to be in the country, you will have serious bother when you try to leave. This happened to me out of the blue last month. My re-entry permit was cancelled as I left to go on holiday, because the police did not update it when I transferred my ARC in April, and I could only get back into the country on a 30-day non-extendable visitors visa, seriously complicated the validity of my ARC. The schools will not help you as they claim that the work permit and visa are completely separate, but unfortunately they are linked. Make sure that both are in complete order before you go on holiday and save yourself the potential hassle!