Hi, welcome to the Forums
My own father served with 5 Squadron in the early 1960's at Lauthala Bay.
He was on the electrical side of things for the Sunderlands
Yes, you're right, the base did become a University, the main hangar survived
for quite some time, until termites rendered it useless, so was torn down.
(late 1990's -I think from memory)
The breakwater is still there- not sure how much of the rest of the base still exists
For contacts, I would suggest contacting the good folks from the 5 Squadron Associationhttp://www.5sqnassn.org.nz/
Hope that helps you