"I have not been able to find 'Server app on the Mac App store yet"
That's because it's called OS X Server and not Server app.
"I need it for administering my other servers 10.4.11 and 10.7.4 . . ."
You're going to have to rethink this. This Apple support article should make things a little clearer?
Basically with your new hardware and OS you're going to have to remote in to those servers and use the server administration software that way.
So much of seemless staggared upgrading of my Apple assets, hardware and or software.
I did read the artical and accept that I must upgrade all my assets at once to maintain a tight level of integration. Let me restate the question, "where on the Mac App site can I find the Server app", the product the second sentance of the first paragraph in the OS X Server (Mavericks) section of artical http://support.apple.com/kb/HT1822?viewlocale=en_US&locale=en_US refers to?
I was hoping someone that has had this issue before could point me to where the alleged "Server app" for Mavericks OS's can be obtained.