What should the inside of this vent look like? Mine has a grate like plate inside, but that is all - is that correct?
The car has what sounds like an exhaust leak, but one shop said they believe the sound is coming from here, and they implied that there should be something else inside this canister that would muffle the ticky sound.

 

That is the downdraft tube that is designed to carry crankcase fumes down under the car where the draft under the car will carry them away and keep them from entering the inside of the car. I am pretty sure there was one that was just a straight tube. This was what the did in the days before PCV valves. The grate like plate is just a baffle. You just want to make sure it is not clogged.

 

There's a article on hotrodder.com called Draft tube or PVC that discusses the changing from the downdraft tube to PVC. interesting enough ,I thought you might want to read. Larry