I checked continuity on the wire to the external horn this morning and installed the horn. Then I checked the wire to the keypad by the garage entrance and I installed the keypad with the flush mount kit. It was all very straightforward.

I programmed the names of some of the zones and set them all to DISABLED for now.

In the next couple of days I'll enable the motion detectors and then we should be able to set the alarm (and it will actually do something).