id confirm the video on the monitor first, ie connect one of the cameras direct.
But usually its due to a badly made off or faulty BNC connction on the video out.
Id advoid low cost rf transmitters etc. We dont sell any of the lower cost units as we havnt found one we think has acceptable performance.
RF transmission is possible but id olny recommend the better brands for this.
http://www.securitywarehouse.co.uk/catalog/index.php?main_page=product_info&cPath=1_59&products_id=478
Thats only 1 end obviously
The 70m is not simple.
I wouldnt recommend any LED emitter to achieve that range, but it is acheivable with the right camera / emitter combo etc
Id recommend the secware pro IR domes for the shorter range views.
http://www.securitywarehouse.co.uk/catalog/index.php?main_page=advanced_search_result&search_in_description=1&keyword=secware+pro+520
you can either use something like this
http://www.securitywarehouse.co.uk/catalog/index.php?main_page=product_info&products_id=2241
that will connect to an analogue port on the pbx
there are ip / sip variations
The current required by the smart is minimal so your main concern will be the lock.
But any 12v PSU will be fine. Id recommend the elmdene units.
ie
http://www.securitywarehouse.co.uk/catalog/index.php?main_page=product_info&products_id=606
the voltek unit is a switcher only. YOu can link multiple switchers together etc
But you will need a voltek PIR to trigger it.
That way all the lights wired to the switcher will work together. But be sure not to overload the switcher. ie 2300W. (tungsten)
Conventionally you would join the returns from one tamper pair to the feed of the next. You shouldnt need to build a series junction box etc. It is one way of doing it however.
I dont know that brand im afraid. You could fit a response pager to it, but i would suggest you contact the installer and or maintainer.
If you let us know the area, im sure someone here can offer their services.