ready to run Ubuntu 12.04 on a USB drive

[Lenny]

Hi,
I just installed Ubuntu 12.04 on a thumbdrive, and I haven't booted up yet.
I will be using Orca.
>From what I read from this list, I take it that most of the Orca users are 
using Unity-2d.
Is this still the case, or have any of you found a way to install Gnome, and 
how difficult is that, if I go that way?
If I recall, I will boot up, and as it goes right into Ubuntu, since it is 
on a thumb drive, I will need to log out, and do control + S, or should I 
call up Orca before logging out?
Thanks.
BTW, I get messages in digest mode, so how do I reply to the list when it is 
a message that is only in the digest message?
Thanks again.
Glenn