Transfer files and update firmware without Connectivity Kit?

[nlj]

Can the Prime be mounted as a USB mass storage device, or is there any other way to transfer files between a Prime and a computer without using the Connectivity Kit?

Also, is there a way to update the Prime firmware by first putting the new firmware image file on the Prime? (Many devices that can behave as USB mass storage devices can update their firmware either automatically when they detect new firmware files in a particular directory, or on demand and I'm hoping that the Prime might be able to do this.)

I'm contemplating buying a Prime but the thought that I might never be able to update the firmware is giving me considerable pause.

[I don't have any machines running Windows or Mac OS; all my machines nowadays run GNU/Linux or GNU/Linux-Libre (and I don't run proprietary software on them) so unfortunately using the Connectivity Kit is ruled out.]