That's interesting...
On first boot from usb we don't get a choice of who we are - guest is assumed?
Launched Terminal and typed firefox, which duly launched. But terminal did not return to prompt so obviously typing pcc was ineffective. Closed terminal and, of course, it wouldn't re-launch!
So, thought I, what if I log out and log back in again (as guest) - and everything seems to behave as it should!
...what's going on with first boot - and will it be the same if/when installed?