Right. Where to start!
....when you plug the iPod in, I imagine that iTunes opens automatically and syncs to the iPod (it does this unless told otherwise).
Next time you do this, look at the screen for your iPod on iTunes (select it by choosing your iPod from the list of stuff on the left of the screen). You will see that it opens with a 'summary' page. This tells you how much space you have used, and allows you to alter a few other things if you want. At the moment you probably don't.
....the top of this screen has a number of tabs (entitled music, video, podcasts, photo etc) If you click on the tab you will see a menu asking you what you want to do with the material there. I imagine music is the biggest file, and as you have too much to fit on your iPod at one time, you will need to click 'selected playlists only', this allows you to choose from the list of playlists below. Only the music from those lists will synch to the iPod, but nothing will be lost from your computer, don't worry!
...to create playlists do the following: Look at the list on the left of the screen. At the very bottom you will see a + sign. Clicking this creates a new untitled playlist, you simply type the name (say, 'kid's stuff') in the highlighted box Once you have created this, you can drag and drop the stuff you want into it. If you want this playlist on your iPod, tick it on the list I mentioned above. If you don't, then, er, don't!
... there are two reasons why CDs are untitled. Either the computer was not connected to the interweb when you loaded them (so iTunes was unable to check them against online database) or they are not recognised by this database. There are very few that are not. The only ones I have had to title manually are Roald Dahl audiobooks from the library.....
Hope this is of help.
....the bottom line is, feel free to play. You won't lose anything. To delete music you have to delete it from the computer, and iTunes will always double check that you really want to do this. even if you do, you can recover it from the recycle bin. And also, don't worry about deleting from a playlist. The music will move from that playlist, but will remain in iTunes!