Migrating from WinXP Pro to Ubuntu 10.10

[Richard Owlett]

I'm a senior citizen migrating to *nix whose last formal course 
work used 026's and line printers for I/O. My personal systems 
have progressed from CPM80 (Digital Research) thru Win 3.1 to 
WinXP Pro. Some of my personal preferences are shaped by that.

I have Ubuntu 10.10 up and running in test mode from a USB drive.

My first impression is that the default installation tries to be 
"all things to all people" while NOT supplying some specific 
tools that I want.

I asked essentially these questions on another forum. After 
receiving some generic Linux answers I was pointed to this list.

INSTALLATION QUESTIONS:

Can I have a pruned configuration be my typical boot?

Can I modify anything on the test configuration?
   I discovered that on reboot I had lost changes made to desktop.

Can I install to the USB drive *WITHOUT* writing ANYTHING to the 
hard-drive?
   Related to my motivation for running the test from USB.


ACCESSING INTERNET:

While browsing files available thru the default desktop, one 
seemed to say that internet access via an external RS-232 dial up 
modem was not available with standard drivers. BUT when browsing 
the descriptions of installed software it appeared that pppcfg 
(IIRC) handled that. I'm confused. My modem is a U.S. Robotics 
5686 model 0701 {V.90 56k - yes is old}


I didn't spot any reference to firewalls or ant-virus tools. Is 
that accomplished in a different manner in the Linux world?

GENERAL:
I wish to end up with
GUI         - exists
Open Office - exists
Tcl/Tk      - have appropriate executables on CD?
Scilab/SciosLab - will have to download
SeaMonkey   - have strong preference for the suite approach

Thank you.