Notes/Domino 6 and 7 Forum : Migration Exchange 5.5 SP4 to Lotus Domino 6.0

Hello!
I have to do the following:

Migrating 600 Exchange/Outlook-Users to Lotus Domino 6.0.

Now I have several questions:

Situation: The Domino-Server already exists with the corresponding 600 person-documents (and ID´s). At the moment, Internet-emails with username@company.com are received by this Domino-Server and are forwarded (forward-address in person-documents) to the Exchange-Server. The Exchange-Server receives mails (from a SMTP-server hosted by another provider) addressed like this: username@country.company.com. (This was not my idea, this situation is due to some "Management-decisions"...;-) ).

- Which tool would You recommend? The one from Binary Tree, the one from Lotus Notes / Domino itself (DUS), or any other migration-tool?

- There is a 2MBits connection from the Exchange-Server to the Domino-Server. Each mail-file is about 50MB. How long will it take to migrate all the mail-data to be migrated?

- Will there be any problems because the person-document/ID´s already exists?

- How many days of work should I calculate for the whole migration?

Thanks in advance for any informations!!!

greetinx

Mike