My ex2007 certificate will expire soon.  If I renew it on the ex2007 server.  Do I need to do anything on the edge server?

It depends on whether you configured Edge to use that certificate.

Hello,

If your certificate had expired in any server roles , you just need to correctly renew the expired certificate and assigned it service timely. Only for renewing certificates in Exchange Edge server role, you need to do more work.

The Exchange Edge server needs a certificate assigned to the SMTP service that can be used to achieve secure connections with outside servers or for authentication with the inside HUB transport server, if there's an Edge subscription in place.

Therefore, after renew the certificate we need to rebuild the Edge subscription. In order to do that, you could follow these steps:

1. On the Edge server run: New-EdgeSubscription FileName "C:\EdgeSubscription.xml".
2. Copy the EdgeSubscription.xml file to the internal Hub Transport server.
3. On the Hub Transport server remove the existing subscription, by running the cmdlets Get-EdgeSubscription and then Remove-EdgeSubscription.
4. Create the new Edge subscription by using the EMC or by using PowerShell: New-EdgeSubscription -FileName "C:\EdgeSubscription.xml".

Hope it can help you.

Best regards