user(s) question

[rikona]

When I set up Ub, it asked for a user name. It seems that that user
has su privileges. I'd like to use that name as a non-su user for
normal logins. If it was RRR, can I change it to RRRadmin, for
example, keeping the same UserID and privileges, and add another
non-su user named RRR? Or - is it better to just add RRRadmin as
administrator, and set RRR as a normal user?

I assume RRR is not root, but it didn't ask for a root pw. [Also, I
have a rtkit group - I hope it's not what it sounds like... :-) ]

RRR would have a modest, but pretty good password, and RRRadmin would
have a very good pw - but - not one I'd like to have to keep entering
with lots of sudo's. Is there a way, while logged on as RRR, to fire
up a terminal as RRRadmin, become su, do the tasks as needed, and exit
terminal?

I copied about 200+G of files to the new Ub, and added an old 1T data
disk, but they had the old UserID from Mandriva [but the same RRR
name]. In trying to reset them[with sudo], I got a 'can't do it' msg
for some files. Is there a way to ID which files have a 'strange' ID
that I can't change in a mass-change operation, or something that
would force the change anyway?

Thanks,

   rikona