For the SK602, if we place the sensor in the garage, will we receive alerts if we have the receiver unit inside?

The short answer is yes for most North American houses.

You house and the garage should be a wood frame structure with vinyl siding. 

The system will not work well if:

• House built with concrete and brick. 
• House has aluminum siding. 
• Sensor or receiver is in a metal enclosed space, like mail box. 

The system would work but with reduced performance if:

• Sensor and receiver is too far away.
• There is obstacles in between sensor and receiver.