Good evening my dear :)
For me, there are 'studio albums', 'live albums', and 'compilation albums'.
Greatest / Best Of albums are compilations, though some do contain previously unreleased songs, usually left-over from studio album sessions.
MQ2: Ooo...
Stevie Nicks ~ "The Enchanted Works of"
Fleetwood Mac ~ "The Chain: 25 Years" [4CD version]
Mike Oldfield ~ "The Platinum Collection"
MQ3: Depends totally on the band / artist and the album.
For example, with both Mike Oldfield and Jethro Tull, with quite a lot of their music I'd say "whole album", but with some other bits I favour individual songs.
BQ: I like some {mostly the "Goodbye Yellow Brick Road" album} - but really depends on my mood.
BQ2: Not doing it for me, sorry.