I don't see the CarloopPro listed any more. If I remember, it included a Carloop, a Particle Electron and a GPS. The GPS it included is the old one, which I think the Carloop guys are working on replacing with a newer higher performance GPS (take that into consideration).
I think you answered your own question without realizing it. Yes, you can transmit data over the cellular network with an Electron. Yes, that data includes GPS data. I think there is example code to even do just that. However, how much data you send will affect how quickly you go through your data plan. Your device will do pretty much anything you program it to do; search for the Particle Electron projects to get an idea of what is possible ... it goes way beyond just Carloop (but Carloop is one of the coolest uses).
You can take the Electron out of the Carloop and install it on a breadboard or in other products. Check out more at Particle.io. When it comes to testing, it often makes sense to use a Particle Photon (on WiFi) to save from using up your cellular data. The Photon and Electron are very very similar, except in battery management, sleep modes and of course Cellular vs WiFi.
As for CANbus testing on the bench, you could do a setup with a CANbus simulator on the other end. I know some people have used a RPi3 to make a CANbus simulator. If you use a RPi, you will need to put together (or buy) a CANbus transceiver circuit.
As for guides, the complete documentation for the Electron is in the docs on Particle.io. The docs specific to the Carloop part are here at Carloop.io. Also, search for projects that other people have done with Carloop; often you can borrow/share code with them.