Explicitly update iTunes Match after adding new tracks to the Library

You may not be able to get complete matches, but here's what I have been doing in the cases where one or two tracks don't match.

1. Select the item(s) to attempt to re-match.
2. Right-click on them, and select "Create AAC Version"
3. When this is complete, hit alt-backspace, and choose to remove both the original and the iCloud version. Also choose to delete the items from disk.
4. Go to the "Store" -> "Update iTunes Match" menu item.

Note that this will keep the play counts, etc on your tracks. It may not succeed on every track, and sometimes repeating the process picks up another track.

Occasionally, I'll get a "Removed" icon there after doing this: just right-click and choose "Add to iCloud" on these.

Yes. The iTunes Match Library icon shows up from time to time (I haven't figured out what the exact requirements are) and you can re-scan your library.

Once you changed your id3 data, select the songs, right-click and select "Add to iCloud". This initiates a re-scan in iTunes Match as well.

If you add music, it will by added to iCloud instantly.