the first 4 points are all you need to know
I think you've missed a trick with point 3 (potentially - I doubt if they are doing this, but it is at least feasible).
You say that to use a VPN you need to run something on the pC, but you don't. The USB stick can have onboard processing sufficient to set up a VPN tunnel, and then present it's interface to the PC (or tablet or whatever) as a USB network interface. Thus the processing is done on the stick for VPN, a normal USB network driver is all that's needed on the PC.
Of course, the stick will require access to a network. If it is WiFi then it's all sorted, otherwise... dunno, but I think your point 3 would be relevant then