Bob Noel wrote:

if you both have similar experience, the difference should be zero.

I was once a named insured on a friend's 180, he had 3000+ hours
I only had ~500 hours. We were both IR. The cost difference was
less than $200.

When we added a third pilot to our policy, they charged us about
$100 more. The pilot in question had way more experience than
both of us added together, including several hundred hours in
make and model and an ATP. Go figgur.

I agree it shouldn't be much, but they may well charge more.

Second question: He doesn't fly much at all. Perhaps one a month or so.
Taking into account that I will be selflessly devoting time to keeping
his bird well-oiled and used to flying, what's a fair price to pay
him per Hobbs hour?

What we did when we had a flying partner, was take our last 2 yrs
maint. expenses and divide them by a reasonable number of hours
(I forget if I used 100, 150 or 200). Then I took the cost of an
oil change plus added oil and divided it by $25. He had a choice
of flying "dry" and buying his own fuel, or flying "wet" and adding
the fuel cost at our local airport in, too, using our account w/
our discount.

IIRC it came to $50 or $55/hr wet and $30 dry. Tach time, since
that's what the maintenance was based on and since I threw the
inop Hobbes in the trash just after buying the plane.

He also washed the plane for us and did small repairs. This was
counterbalanced by breaking small stuff on a regular basis, no
apology, always the stuff's fault and often didn't tell us I'd
just go out to find it missing and tossed in the back. Which
I got tired of, so we ended the arrangment when my daughter was
9 mos old and I was able to start flying again.

Cheers,
Sydney