As I understand, with a working holiday visa you only get to work a maximum of 4 months for the same company?
Can I get a serious job or will I be stuck plucking fruits and waiting tables?
What happens for many well-qualified people is that, since the WHV is an open work visa entitling them to take any job (temporarily), a company will take them on, see if it looks as if they are going to fit in, then, if so, make them the offer of a permanent job. Once that offer is in place, they can then move on to a temporary work visa of some kind.
http://www.immigration.govt.nz/migra.../requirements/