My new server is now at home and I’ve started the migration process.
So far, all the mail stuff has been ported (Exim, Dovecot, SpamAssassin, ClamAV & Mailman) without too much of an outage.
As I’ve altered the port forwarding on my external router, there should be no need to update any settings :)
I’m going to to decide whether to do the Apache / FTP migration today or leave it until tomorrow or Monday. Probably the latter.