Sendmail/Exim and IP-Address

Hello,

I started looking into setting up an MX on my LAN, by reading info at
Sendmail.org. I have a fairly static IP address, i.e. not guaranteed to
NEVER change, but never does. It is VERY (34 char) long,
"cpe-24-221-41-162.az.sprintbbd.net", and

(1) I'm wondering if mail sent here would have to be @this_long_address, or
if there is a way to alias it shorter.
(2) Will I be able to configure a mail server so that
    (2a) fetchmail will forward retrieved mail to the mail server
    (2b) where it can be retrieved by the user on the LAN?
(3) Can the mail server be on the DNS server as long as they have the same
name and don't slow each other down?
(4) IF mail does have to go to webmaster@this_long_address, then it is over
40 characters...
    (4a) too long?
    (4b) Then mail will hit the router and be forwarded according to the
port/firewall setting to the mailserver box, right?

Thanks,
Rod