My query is... whats it like to tow? Obviously the Delica can tow, as many have shown here and in the Canada forum. I'm set on a manual diesel; I see above that @Growlerbearnz mentioned 3500rpm in 4th at 60mph, although I'm fine doing 55; I'm never in a rush, and the kids have 12 bathroom breaks an hour anyway.
How loud is it? Probably fine in the back, but will my passenger hate me?
Tire size; many people put 30" tires on, but I'm thinking to go back to stock (28"?) to save some rotational mass and power. Or is that a mistake with how low the gearing is already on a Delica?
A Delica should tow the teardrop just fine. It's slow, but not dangerously so.
If you get a wagon model (people mover, chassis numbers are PxxW - the W is for Wagon) it's not too loud as long as you don't fit a straight pipe exhaust. Not modern car quiet, but you can have a normal conversation. The van models (PxxV) are noisier as they're built more economically.
I prefer the larger tyres as the high engine revs get tiresome after a while. The diesel has so much torque that rotational mass is barely noticeable. Try to go for narrower tyres if you can (9.5" or 235) as wide tyres will give you worse fuel economy.
If you're towing and have a van full of luggage, your passengers will appreciate some air adjustable shock absorbers on the rear (MA708, check out the FAQ here). The rear springs on most Delicas are getting tired, and even a small trailer will cause the rear to pitch if it's under load.