Key Signing, Subkeys

[g_k at gmx.at]

Hi!

I'm new to GnuPG and have 2 questions regarding key signing I didn't find 
answers for in the documentation:

1) Somebody signs my public key, and this "new version" containing that 
additional signature is uploaded to a keyserver. (Am I right so far?)
How do others that already had my public key before that signature get the new 
version? How do they know there is a new one?

2) When I have a master key, and a subkey for everyday usage, I don't lose all 
the signatures on the master key if the subkey is revoked or expires, since 
the new subkey will be signed by the master key. This implies using only the 
master key for signing. Now, if someone signs my master key, how will this be 
reflected on the subkey? Do I have to generate a new subkey every time 
someone signs my master key in order that the new signature affects the 
subkey?

Thanks a lot, georg