Permits is the way your jurisdiction funds it's building department. For that
you get an inspection or two.
Mainly you get the permit so if one of your neighbors "rats you out" you will
be covered.
"Insurance" is bull****. The "inspection" is so minimal that thwere is no
aassurance that you actually did the work right. Insurance companied know that.
Your rate might change because of specific additions you add (like a pool) but
that is really just a call to your agent. If your insurance company is going to
screw you, they are going to screw you no matter what. Get a better insurance
company.
Sometimes the inspector barely even gets out of his car. It is not his fault,
they are expected to do between 20 and 40 a day depending on where you live and
how much construction is going on there. I always read that you should "ask the
inspector". In most places the answer you get is "I am an inspector, not an
instructor". Maybe if your wife is wearing "Daisy Dukes" and a wet T shirt she
can get a conversation started but usually the inspector is too damned busy to
say more than yes or no. I had 5 inspections on my pool, I was there every day,
I actually saw the inspector twice. The other times I think he didn't even walk
around back.

BTW don't be shocked when you see how much permits cost. A shed permit is $145
in my county and $40 more if you want a light in it. If you are just setting a
prebuilt shed it is "only" $100.