All the trains don't go by those terminus, and some never go by those terminus, they have their own terminus.
Each destination is related to a different name for the rer.
The rer C train serves all the Paris zone, with 16 stations in Paris (zone 1) from Porte de Clichy to Bibliothèque François Mitterand, as well as Javel and Pont-du-Garigliano. You can use your ticket t+ within this zone.
The frequency depends on the branch, destinations, days of the week, the hours of the day, off-peak hours or rush hours.
In rush hours, for the common journey, you can have train every 2-3 minutes, just to have an idea of the frequency, however it doesn't mean a lot because, the train may not to go on the desired location.
Here is the rer C map.
To have a better understanding of the zone covered by this Paris train line, you can check the Paris zones map (you can also find those two maps on the Paris rer map post).
The rer C is a widely used line for tourism purpose because a lot of different attractions are located on this line. Indeed you can go and visit the Tower Eiffel, le Pont Mirabeau, le Champs de Mars, le Trocadéro, les Invalides...
The rer C is connected with the rer B in 3 stations and with the rer D in 1 station (Juvisy).