I work as a roofer that specializes in roof construction
Do you have to go to school for that? 
roofers have to be able to work,. have good motor skills and have great carpentry skills, too.
Is it hard work?
yes! especially because of the application of materials that waterpoorr and weatherproof buildings and some are on raptops, trusses, frames and hard angles!
I would think that a typical roofer could not work thirty years and then retire, do they have a retirement age?
none that I know but you're right in that they have to be able to be a constructioin worker specializing in roofs and can be dangerous and hot!
Do they have a high mortality rate then?