To get to tauranga from auckland you can bus, look up Intercity bus company (they will get you there for about $35) or Naked bus company who has specials and quite low prices generally. If you are hiring a camper van or car the best way to get to tauranga is to take the southern motorway out of auckland and then take the tauranga, coromandal exit off the motorway
check this out for exact directions from auckland airport to tauranga
http://maps.google.co.nz/maps?hl=en&tab=…
as for backpackers, there are plenty, look them up when you get into new zealand or even on the internet, they wont be that hard to find and most are happy to take you on a walk in basis without a reservation
