conventional fire alarm system (diagram) fdas 

Depending on the building's layout. A detector should not be more than 6m from any wall or obstruction, and no more than 12m from another detector.

As the name suggests EOLR should be installed at the end of a security loop. In most cases, EOLR can be only installed at the end. That is because if it's not, the effectiveness of resistor is lost.

The detectors that aren’t marked are not polarity sensitive, as long as your negatives and positives line up it will work wired either way

Sounds like a bad connection for a specific device, look at the report it will tell you which device this is and check the wiring

To get 24v

It depend on the brand