[Trisquel-users] Re : Questions making boatable usb with writeprotection and some stuff

[magicbanana]

Those questions are indeed many and not their answers are not trivial.  
Anyway, I will give a try and invite the remaining users of the forum to  
correct my errors:

The startup disk creator can erase files on the USB stick. Those files may be  
owned by anybody (although they are more probably owned by nobody because  
most USB sticks use the FAT filesystem with no notion of ownership and  
permission) and administrative privileges are needed to do so. At least, that  
is my understanding.
I do not think there exists any freedom issue with USB sticks: Linux-libre  
can drive them all.
I see no reason why you could not. You then want a startup disk with no  
"extra space for storing document and settings", i.e., you want to select the  
last option "Discarded on shutdown, unless you saved them elsewhere" in the  
startup disk creator. With any write blocked, the USB disk would then be  
equivalent to a CD/DVD.
As far as I understand, the Live system is directly installed on the device,  
not in a partition of the device. In other words, the installed filesystem(s)  
should not make any difference for the Live system.