Okay - answers to your questions:
netbios name should be the name displayed when you type set at a command prompt - use the USERDOMAIN variable, but only the first 15 characters if you have a long name.
Realm is fine
Any certificate issued to a .local address will never work. It has to be a name that resolves in DNS so you will need to reissue your certificate with something like mail.domain.com
FQDN locally is fine as an A record.
iPhone settings:
Server - mail.domain.com (needs to resolve in DNS and match the name on the certificate)
Domain - just domain
You will never be a pain. If you are not sure - asking is the best way to find out and if I have not spelled it out in my article, that's my fault ; )