Can the Motion Alarm be linked to Wi-Fi? And can one remote control link multiple products？

No, not support Wi-Fi. The Remote Control can link up to 5 Detectors. And one Detector can link up to 5 Remotes, too.

When the intruder goes off, can the alarm automatically turn off?

If you don't manually turn it off, it can do that automatically after 2 minutes. It's worth mentioning that if work by batteries, generally, the items can continuously working for four months.

Can the Remote Control and PIR detector work effectively though windows, glass doors or walls?

PIR technology can not work effectively through glass or wall, so the Detector will can not detect the human movement single. But Remote use radio technology which can still work effectively.

What is the working range of the PIR Motion Sensor Detector?

The Detector can Capture signal between 45 degrees up and down and110 degrees left and right, which is about 16-26ft detection range of the infrared sensor.

Are this Motion Detector used for outdoors?

No, the Motion Detector can just used Indoors, it is not water-proof.