To see what a model is likely to have at Hertz I usually look at their used car sales sites to see if they have any of them for sale. They do list many Camrys with Satellite Radio. They also lost some without it.

As to an upgrade, you will most likely have to ask for one to see if something is available. When you reserve this exact model, they assume you want that exact model, and probably get as many people upset they were upgraded from that exact model as happy to have an upgrade.