CAL assignment: license your server, grant yourself access to the QMC, open the QMC (QlikView Management Console) and consult the Help. Named CAL assignment is in system->Licenses->Select your QlikView Server->Assigned CALs. To assign Document CALs, you first have to publish documents. As soon as you have those, goto Documents->User Documents->Select document in tree->Document CALs.
Some info is available in the Server Reference Manual, but most of it is easily accessible in the QMC Help.
Download NPrinting Server: register yourself as a customer on www.qlik.com. Log in, goto Support->Customer Downloads (you'll be presented with a QlikView application for all downloads), select the QlikView tab and from the product list select QlikView NPrinting Server. Click the particular installer that you need, and a download will start automatically.
Evaluation copy: if you mean by this a time-limited license, then you'll do just fine until the license expires. There is no feature difference with a QV Desktop that has a perpetual license. If you want to migrate from the temporary license anyway, remove the license in QV Desktop by opening the application and selecting Settings->User Preferences->License. Click the "Clear License Information" button and close the dialog. Your QV Desktop will become a Personal Edition (PE).
A Personal Edition QV Desktop can be licensed from a server by following these steps:
In QMC, assign a Named CAL to your Windows account. Only Named CALs can be used to license a QV Desktop and only Named CALs can be leased. From your last post, I get that you may have done this already.
On your personal machine, log in as the Windows account with a Named CAL.
Open QV Desktop.
Select File->Open in Server...
In the top field, enter your QlikView server name like this: qvp://servername and click Connect (replace servername with the name of the server on which you installed QlikView Server)
The other fields will show one or more directories and one or more QVW files.
Select one of the demo QVWs and open it.
At that moment, and if everything goes according to plan, a Named CAL will be leased to your QV Desktop for at least 30 days or until the Named CAL is revoked.
You can check the licensing state by selecting License Information under Resources on the Start Page. The dialog should display something like "QlikView User License (using license lease from server)"