I believe the rear defrost is also for the heated rear view mirrors in addition the hard top. OK what Steve said.
The forward handle that is broken is for the seat height adjustment. It controls a pneumatic shock that raises the seat. Some people sit in the seat and pull the lever, when it doesn't do anything PULL HARDER.....
When you are in the seat you kinda have to levitate yourself up so the seat can rise. Or before getting in pull the lever. Anyway yes get it fixed.