Dear Venkat,
1) Please check sap note 496819. It may be helpful for what you are looking for.
2) Please explore the maintenance of table TSAD3T and if it serves your purpose you can manually synchronize it across landscape. However maintaining the word 'Dear' in title may be over doing it in case some email templates are using this field then the outgoing emails can read Dear Dear Mr.
Regards
Shivraj Singh