Hey there,
Regarding the second question, to have all your audiobooks in one tab:
- select the files > right-click > send to > audiobooks
- to display the audiobooks tab, first make sure that it is ticked in Edit > Edit Preferences > Layout (1)
then click the + button like the one on the screenshot below, and then choose the audiobooks navigation tab from the sidebar on your left.
- to create a playlist based off of audiobook files only, select audiobooks as the source when creating your playlists (see image below)
I might have misunderstood what you're looking for though.
I already spend hours on end on social media. Might as well spare a few of those to a greater purpose here.