On my laptop I have 2 internal drives plus an additional 2 USB external drives, one which I connect occassionally, the other very infrequently. My library is spread across all 4 drives. I make sure that my 3,4 and 5-rated tracks are on the internal drives, and the 1s and 2s are on the external. Additionally, any 2s that are frequently played get moved to the main drives.
This means that I have tracks belonging to the same album spread across 2 or even 3 drives--a necessity given my disk drive constraints. While this may seem hopelessly mangled, MC handles it all seemlessly. I see contiguous albums, and the MC icon indicates whether the track is present. As for tracks on the USB drives, MC will remember them and reconnect them when the drive is brought online.
Under tools/auto import options/auto import folders/options, be sure to select either "fix broken links--no", or "fix broken links--yes (protect network files)." Also, benn's advice is good regarding the lower-alphabet drive letters.