Hello.
I'm sorry to have to tell you that the Resident's visa which you had (then called PR with RRV) ran out, as you suspected. You would have had to apply for the next one within six months of the expiry. Therefore, since you didn't do that, you are now in the same position as if you'd never been a resident at all. It is too long ago just to apply on the basis of what you had back then.
To live and work in NZ as quickly as possible, you will probably need to apply for a work visa first, and you will need to get the offer of a skilled job to be eligible for that. Here are links to two possibilities for work visas.
https://www.immigration.govt.nz/new-...ills-work-visa
https://www.immigration.govt.nz/new-...residence-visa
To look for work in NZ, you can go in as a visitor, stating that your purpose for the trip is to 'look, see and decide' (on the card you fill in on the plane, if you're a UK citizen who is going in on the visa waiver basis).
http://dol.govt.nz/immigration/knowledgebase/item/1135
Once you get a skilled job, you can apply for a Skilled Migrant Category Resident Visa
https://www.immigration.govt.nz/new-...-resident-visa, which is the present-day name for the same kind of visa you got back in 2005. After holding THAT visa for two years, you would then need to apply for a PR, which is on the basis of that page you found that talks about commitment, 187 days in 12 months, etc.. But you are a long way from needing to know about that, yet.