Hello and welcome.
You will find there is MUCH less formality/proof involved in going for a partner-sponsored Residence visa than in trying to get a visa independently, especially as teaching has recently been removed from the list of skills urgently wanted. See here.
http://www.immigration.govt.nz/migra...ly/default.htm It is possible for them to be processed very rapidly, once your evidence is in place (they're prioritized as they want their Kiwis back!).
Basically, the only qualification required (beyond the police check and medical required of everyone) is to be the partner of your partner, and having a home in joint names is only one possibility on the list of many. Look at the Operational Manual, F2.20
http://www.immigration.govt.nz/opsmanual/index.htm (go to
Residence » Family Categories » F2 Partnership Category » F2.20 Evidence), and also old threads on here, for what people have supplied.