backup all keys of DSA+ELG pair?

[Kārlis Repsons]

On Friday 05 June 2009 15:23:10 Werner Koch wrote:
> On Fri,  5 Jun 2009 16:59, jh at jameshoward.us said:
> > On Fri Jun  5 10:52:48 2009, David Shaw <dshaw at jabberwocky.com> wrote:
> >> --allow-secret-key-import is a no-op.  It is no longer used for
> >> anything.
> >
> > Really?  I could not import last week without it.
>
> Sure:
Ok, but I am still in problem, because, after I did 

thekey == mail address
Machine 1: gpg --export-secret-keys (thekey) > myfile.gpg
Machine 2: gpg --import myfile.gpg

it says 

gpg: Total number processed: 1
gpg:               imported: 1
gpg:       secret keys read: 1
gpg:   secret keys imported: 1

However, I had there 3 subkeys today! And after doing import, they all appear 
through gpg, but no way to use any with kmail!
I also tried thekey == key ID, but it gave equal outputs for all the IDs...
What is wrong?

Actually, I would appreciate, if someone explains me the concept of master and 
subkeys in gpg - 
1) the exclusive/overlapping functions of them
2) does fingerprint change, if subkey is added (or, does that refer to the 
master key only)?
3) how about the revocation certificates, that are generated for master key, 
if signing subkey is added afterwards?

Thanks for responses, its nice to be in touch with free software people!

k.