changing the shell prompt

[David <dpleydel@univ-fcomte.fr>]

My current shell prompt in emacs shows as...

^[[01;32mdave@dell-1^[[00m:^[[01;34m~^[[00m$

actually, reviewing this email in a terminal I don't see all that
mess, instead I just see

dave@dell-1:~$

If I change directory the directory path gets included, e.g. in emacs shell...

^[[01;32mdave@dell-1^[[00m:^[[01;34m~/programmingTutorials/kernighan_n_ritchie^[[00m$

which in the terminal shows as ...

dave@dell-1:~/programmingTutorials/kernighan_n_ritchie$

I know I can change the shell prompt at the command line with 

PS1="$ "

I have three questions.

1) How can I configure the emacs shell with a simple default shell prompt?

2) The usefulness of inclussion / exclussion of path in the prompt is
task and path dependant so is their an easy way to toggle this option on/off?

3) How can I stop emacs displaying rambling strings of code at the
shell prompt and to show instead the information that the code is
suposed to convey (as in the terminal).

4) If the path is very long and takes up a lot of space on a line can
I just display the last two or three directories in the path or
perhaps the first and last directories seperated by ... ?

OK, not quite three, but anyway... ;o)
peace
Dave