Touring lower half NI to Entire SI, recommend a bike and some gear sub $5k?

Im on a totally budget as Ive been ill for 4 years.

But its either now or never, planning to leave mid November.

Im not really a 1000cc guy, prefer 600s due to manoeuvrability. Always been a naked bike guy, never owned a dual sport. Presuming 250cc is too light weight?

So questions

What bike for about $4k bought in Auckland?

Do I need a dual sport?

Which tent/swag would you go with?

What luggage gear recommended on a budget? side bags and just a backpack stand on the back?

What safety clothing? Flappn just sold my gloves, helmet, boots, summer jacket, the lot as they sat around for 5 years, all bought new lol.

Are there any guides to touring the SI already for bikies?

I have a platform in mid Canterbury to launch my lower SI Assults from and take respite ever week or so. I really want to camp and get to know places.

Any dodgy towns to avoid?

Ive never done the BOP side of NI down, is Napier down a good ride?

How many KMs per day is too many for an unfit person who does suffer back issues at times? (hence the launch points to take respite in a proper bed for a week or so)

Touring lower half NI to Entire SI, recommend a bike and some gear sub $5k?