I am unable to synch music from selected playlists in my iTunes library onto my new iPod Classic, despite meticulously following the User Guide.

Question

I just purchased an iPod Classic, and after making sure I had the latest ver. of iTunes on my Intel MacMini, printed out the User Guide and carefully began learning how to operate the iPod. My first step was to ensure I had manual control (vs. auto synch) because I want only selected songs and playlists on the iPod, not my whole iTunes Library.
On pg. 24 of the Guide is the topic "Synching music from selected playlists onto iPod Classic." Just what I wanted. OK, I selected iPod "in the source list" (aside: Shouldn't it be "in the device list?" I dispair of imprecision). This brought up the iPod Summary page, showing I had selected Open iTunes when connected and Manually manage music and videos. Next I clicked on the Music tab.
This presented me with Synch Music next to an empty check box. Below it, and entirely grayed out was:
Entire music library (showing a checked box)
Selected Playlists, artists, albums and genres (next to an unchecked box).
There's also a third grayed out item: Include music videos that is checked.
When I selected Synch Music, I got the message: "Are you sure you want to removed existing mlusic, movies and TV shows from the iPod and synch with this iTunes LIbrary?   I selected Cancel because:
1. The grayed option Entire Music Library is checked, not mly preferred option of Selected playlists, artists, albums and genres. .
2. I can't find anywhere in the User Guide how to "Select the Playlists" I want to synch to my iPod. At present all I have in iTunes is my list of playlists in the left hand side bar.
OK, my first thought was the checked box in the iPod's Summary window: Manually manage music and videos. So I went there and unchecked it, which immediately brought up an alert  to the effect "Are you sure you want to automatically synch your entire iTunes library, etc. etc...? I quickly cancelled. Thus, I seem to be in a Catch-22 situation. 
So the questions are:
How do I resolve the Synch Music issue so I am assured only selected playlists will be sent to my iPod?
How do I create a list of playlists in my iTunes library to be transferred to my iPod?
How do I manually move a playlist in my iTunes library to my iPod's lists of playlists?
Any help much appreciated. Thanks to all.
John in the Pacific Northwest

Answer 1

For the immediately problem, you can shut down the computer and disconnect the iPod.
There may be a process (program) running on your computer in the background that continuously monitors mounted volumes for things like maintenance, data corruption, and malware.  The iPod's storage is a mounted volume.  If you know of any such program, such as an "anti-virus" utility, and it has settings that allow you to exclude certain volumes, you can set it to ignore the iPod "disk" when connected.
Also, if you are using automatic syncing (not the manual method) to load the iPod, and you have Enable disk use turned ON, turn it OFF.  With Enable disk use turned OFF, iTunes only mounts the iPods disk when syncing, then immediately unmounts the disk.  Thus, other processes you have running on your PC (not iTunes) will have less of a chance to make the disk "in use" and cause this problem.  You won't even have to eject the iPod before disconnecting.