DirectAccess - anyone other there using it?

I am hoping to tap into someone else's experience and expertise on DirectAccess client/server.

Do we really have to acquire a second public IP address for our Internet network adapter?  Also, it appears from the documentation on Technet that the remote clients must be running Windows 7 Ultimate or Windows 7 Enterprise, as opposed to running Windows 7 Professional.  Is that indeed the case? 

Also curious how you configured IPSec on the clients.   Are you using your own PKI or a third party? 

As you might surmise from my questions, we're starting from square one on this and I have never attempted this before.  Our servers are running Windows Server 2008 R2.

Thanks in advance.

Marty