I got a lot of those Unable to open connection to server errors within the first 1-2 hours of doing the configuration. I enabled logging and looked at the logs for the Exchange Adapter component. Near as I could tell, that error would show on the device when there was an entry in the log where a new replication attempt was started while an existing replication attempt hadn't completed. As as I said, after a couple hours, it seems like its all replicated and that error hasn't shown up lately.
After you've configured your account, you should go to Settings > Accounts & sync and click on your corporate account. Ensure 'Sync Corporate Calendar' is selected.
When I opened Corporate Calendar, it automatically fetched about a month's worth of calendar data. I haven't gotten any calendar invites today, so I can't attest to how that'll function. Likely a good chance of testing that tomorrow or Friday.