About your first question - I'd call II and ask why your AC doesn't seem to be picking up inventory that should be available based on the grid. Tell them you know the inventory is there because you can see it with a different week. Maybe, hopefully, they'll be able to book it for you over the phone.
About your XYZ's question - XYZ is an unpublished perk from II that makes extra weeks available to anybody who has a confirmed exchange with a future check-in date in their II account. There are two kinds - one is a simple 2-for-1 bonus week that anyone should be able to get and the other is available if you've exchanged a larger unit than what you've been given.
You'll have to pay another exchange fee for any XYZ week. Both grids are very limited; you have to call II and speak to a rep to find out what's available and get them to book it for you. Not all II reps are helpful (or knowedgeable, IMO) about XYZ's so if you start asking questions and the rep appears clueless, just hang up and try again.
There is an XYZ-related thread on the Exchanging board -
II- XYZ - Lovin' it! - which should answer your questions. There's also another XYZ thread - dealing mostly with inventory releases - on the Sightings/Distressed board but I won't link it because that board is restricted to TUG Members. You should see it on the first page when you open that board.
