To see enhancements and changes, start here and click on topics on the left hand side.
Configuration You will need to access your old server to see what you might have customized or configured previously (there will be changes)|
Go to installing and upgrading and scroll down to BACK Up Files to get a list of all the items you might have configured in the past. Do not copy these over unless your are just moving to a new server and staying on the same release of XCOM, there have been too many changes. Use them as reference when configuring your new XCOM.