Yes, the refrigerant must be reclaimed first. It is a leak-down test, but at a higher pressure than you'll ever see in use.

This is better than checking with vacuum both because of the higher pressure differential (vacuum can only be <15psi) and the direction of that differential (vacuum can help close up small gaps).

The TXV is roughly below the windshield wiper mechanism, and just to the left. Follow the suction pipe where it goes beside the brake booster, and it ends at the TXV. The wiper mechanism and water tray come out to access it.