lisp basic question

I post this though it might be very basic. But I'm using lisp for a 
little while (small didactical project) amd I still did not figure it out.

as everybody know when I type in the interpreter a symbol or a varable 
name, the interpreter answer telling me his value.

example:
 >(setq a 3)
3

 >a
3

but how is it possible to recall the body of a function already defined??

 > (defun p (x) x)
 >(p 3)
3
 >p
error: attempt to take the value of the unbound variable p

It would nice instead that if I type in the name of the function the 
system replies telling me the body of the function!!

second question: how can I save the current environment (binding 
symbols/values, function definition and so on..) of the interpreter (in 
ACL 6.2, of a listener) for load it afterward?

third question: how can I make a script file with command likes change 
directory, load these files and so on?

thank you  a lot
paolo*
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