I agree with Antinode, Sounds very much like it should be a monitored system.
Regarding the PIR's I have found that you do get what you pay for, the GJD's are a good option, but i have always found that Redwalls and the Adpro Pro series are the best out there. The main thing is trying to limit false alarms, especially if monitored, as this can become a major issue later on.
As for auto tracking, there are domes that have this as a built in facility (sony used to produce a system) but iMHO are a bit to easilly defated. However if there is a budget for auto tracking i would suggest looked at an analytics based system that isnt as easly bypassed.
Regarding the wiring, you would have an option with the PIR's as to how to wire them. The usual metod would be to go back to the head that the PIR system is controlling, however if the DVR has the feature of alarm mapping, taking the alarms back t the DVR first with the DVR sending the heads to preset postions can also be a very sucessfull configuration.
Hope this helps,
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