If you wnat to setup a domain in the dns manager, then use the dns wizard to get an idea how the correct records shall look like.
Client: bla bla
Zone (SOA): mydomain.com
You missed the dots at the end of all lines. Use the dns whizard for a correct example.
Should server2 acknowledge somehow that it is indeed dns3 and dns4?
Regarding zone transfer. In a dns server setup that uses mydns in most caeses you use mysql replication or let all dns servers connect to a central database instead of using zone transfer.