Auto import should largely deal with added and removed files correctly. I don't exactly trust the "remove dead links" feature, so I'd probably do that part manually. It's quite easy to build a smartlist that shows missing files:
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Your situation really is kind of a sync scenario. You can actually use MC's Handheld Sync system to sync your home library with your office one. You'd set up a handheld definition that has a target of the external drive where you keep the office library, when you plug it in at home. Then, whenever you bring it home, just press Sync and it will add and delete anything that has changed on the home system since the last sync.
There's a trick here too: Set up the playlist that drives the sync as an MPL format. That will transfer everything over, including all custom metadata. It might be overkill for your situation. You probably still need to manually delete removed files (dead links) on the office system. So I'm not sure if this is the best approach. Just mentioning it as another way you might consider and experiment with. Glynor introduced me to the idea in an old post of his and I found it really interesting.
Brian.