What are the necesary licenses that I need purchase for this upgrade?. The migration will be on new MCS7825.
What is a Feature License?.
Do I need migrate to a version 6 first?.
The CM Software Version License for 7.x is something new and is different than the Node or DLU License. The new "Feature" License is a reference to the Software Version that can be run (in this case CCM 7.x) Without the "Feature" License the CCM 7.x build can be completed but will not run.
When you order the CCM 5.x to 7.x upgrade via PUT (Product Upgrade Tool) you should receive a CM Software Version License for 7.x as well. This just allows you to run the Callmanager services on the new version. The Node licenses and DLU's will be migrated during the upgrade process so they will not need to be re-purchased.
Don't forget to get your existing and new licenses re-hosted to reflect the mac address of your new Publisher server.
As far as a "direct" path between CUCM 5.x and 7.x it depends on what version of 5 you are running and
what version of CUCM 7.x you are going to Check out the link below;
Cisco Unified Communications Manager Software Compatibility Matrix
Tons of great info!