once issued work permit, can you leave and other questions…..

[heiks]

Hi,
I got a job offer yesterday (under skilled migrant category) and have nearly all papers ready for the application for work permit. After that my wife and our children can apply for their work permit/student visas.
Our idea now is to fly back home (we are currently in NZ) in 3 weeks for 4 weeks and come back then and start working. Is this a possible untertaking?
(1. is it possible to gather the permits/visas within the next 3 weeks (I know that my work permit should be available on the same day, if I visit the Imm. office personally (last paragraph at http://www.immigration.govt.nz/branc...ocessingtimes/, but what about the others?),
2. are you allowed to leave and re-enter NZ after having received a work permit (or can I say I want the work permit to start on say, August 15)?
3. if the 3 weeks are too short for all those papers, how else to do it? we need our passports to travel home, can we somehow apply for the visas/permits here and let Immigration NZ send them to us in our old home country (but how without having the passports...)

thanks,
heiko