I'm new to Mac networking , so please bear with me. I need to clarify a few of your steps.

1.Insert the USB with Mac OS X in the Mac device

I'm assuming the "USB stick with Mac OS X" is non server OS X and is being installed in a separate partition from the existing OS X on the" Mac device"?

4. Select Disk Utility to create and name partitions.

This new partition will be where OS X Server is installed? What's minimum size to create the partition?

7. Choose the drive you???d like to install the OS on (most likely the partition you just created) and give it a few minutes to install.

You're installing non server OS X at this point and it will be upgrading to Server OS X in step 20 ?

Thanks for your help.