"What are xmodmap and xev and how do I use them?"
For a simple example see
http://askubuntu.com/questions/24916/how-do-i-remap-certain-keys
xmodmap and xev are standard X command line programs. To learn about
them open a Terminal window and issue the commands
man xmodmap
man xev
In summary, Xmodmap lets you define for a given keyboard scan code
and shift/alt/ctrl etc combination which X keyboard event codes
and/or UTF-8 characters are sent to the GUI. So you could redefine
Scroll-Lock+u to produce the code for the keypad 4 key. Xev is a
simple program that displays a little window and gives you the X
events which are being sent to it. Click on it and press a key to see what
key scan code you need to redefine.
Personally I'd experiment with your keyboard first. Keyboard
controller chips are standard components, its quite possible you have
the function just the relevant decals aren't on the keys.
There might be other solutions we could find if you told us exactly
why you want to be able to move the pointer with the keyboard. E.g.
GIMP has keyboard pointer movement built into it using it's own
keyboard sequences so the specific app you're wanting to use might
provide a similar function.
"And exactly which members of the forum can see my email address?"
The forums are linked to mailing lists[1] and the email address you
registered with is sent on the mailing list copy of your posts. Your
account page tells you about this and the other uses the email
address is put to. There's an old issue open on the topic[2].
[1] http://listas.trisquel.info/mailman/listinfo/
[2] https://trisquel.info/en/issues/2003
