A. No. The upgrade from Exchange 2007 to Exchange 2010 will consist of setting up a new Exchange 2010 infrastructure (which can be part of the Exchange 2007 organization) and then migrating the mailboxes over. No in-place upgrade will be supported.
When you upgrade, you'll first implement Exchange 2010 Client Access server (CAS) boxes, then Hub Transport, then mailbox, followed by Edge and Unified Messaging. You must have an Exchange 2010 CAS and Hub Transport in every AD site that has an Exchange 2010 mailbox server.
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