I have 8.1 Enterprise that I use over a network. It runs with Snow Leopard Server on a Xserve.
Can I update Snow Leopard Server to Lion Server without reinstalling/reconfiguring CAT DV 8.1? Will it work on Lion and will all the CAT DV setting carry over. At this point, we don't use any automation.
Yes but your milage will vary as this has obviously not been throughly tested. I suggest you should upgrade to 9 now and get 10 for free it's a great deal. If you wait you have to buy two upgrades and 10 is quite a bit more evolved than 8.1 or even 9 for that matter.
Is it easy to upgrade the enterprise app and worker node? We had someone configure this for us originally. If it's just like installing any other program then I rather install it myself.
I'd clone the entire drive before upgrading server as that's a simple restore. Barring that, you can dump the database using the "Export" button in the control panel, or in the MySQL command line or other SQL tools.
Also be careful that you install the same version of CatDV Server on the new box. For instance, if you choose to upgrade your version of server (CatDV Server newer versions generally work with older versions of the client so you can do this) then I'd upgrade the CatDV Server app on the old OS before upgrading the OS. If you still have the old installer then you can keep it all the same on the new box. The reason for this is that the installer often upgrades the schema so you can't restore an older db dump onto a newer load of CatDV Server in the case of restoring from a backup.
Additionally Lion does not include MySQL in the OS install so you will need to install a current build of MySQL after your clean server OS install and before installing CatDV. The instructions are in the CatDV Server read me so maybe take a look and decide if you need assistance before it's Friday night before a deadline and you have a server with no db on it and need it to work on Monday am. Those tend to be expensive weekends. ;)
One final note, CatDV is the least of your concerns in upgrading OSX Server from SL to Lion. Make sure to read and follow all of the online docs if you have other services running on that box. Lion has all sorts of "new things" in there.