I am thinking of buying an airplane....I want to rent it when it is not in
use to recoup some of the cost of buying the plane. How hard is it to do
this? What are the insurance costs? How often do I need to get it checked
out by an aviation mechanic? How much is the maintenece? Do I have to go
through an FBO? Or can I just place a classified ad....eg. "plane for
rent...$50 an hour".

As for insurance, you could insure it just for yourself to fly, and then
require your renters to carry renter/borrower insurance for the full hull
value.