I just finished installing a BBHCM371A Web Camera. Since it is outside and needs to be sealed, I created a 3ft. long pigtail that brought out alarm 1, alarm 2, power, trigger output and ethernet and then sealed the unit with the included goo and tape. I made up the pigtail terminations in a 4X4 j-box mounted near the camera to connect to the cables that we ran during construction that go back to the control board
As far as power goes, I cut the wall wart off the power supply that came with the camera and fed it with the central power supply I use for all the automation equipment. In my case, this is a Sola/Hevi-duty multi output switcher which provides closely regulated 5V, 12V, -12V, 24V. (Model GLQ-05-200). In the case of the +12V supply, I've created two "branch" circuits and each is fused. I feed several devices off each circuit and have found the regulation of the power supply to be stable.
I would invest in a good power supply rather than try to count on wire impedance to protect your investment.
By the way, I would be concerned about the trigger output. If your camera is similar to the 371A, then it has an open collector transistor output stage. This is a sinking output and can only handle about 100mA. It may be wise to consider the load that you are planning to drive with this output. If it's a garden variety Potter&Brumfield relay, for example, you may want to look at coil impedance and calculate current draw to be sure you're within the capability of the camera output circuit. Also, if you are using an interface relay or any inductive load, then it might be good to put a diode across the coil or load to dampen high energy spikes that could damage the camera output circuit when the load is shut off.
I use the camera output to turn on the outside lights via my stargate unit. I use the alarm 1 input to trigger the cam to take a picture when our drive alert goes off. The camera emails that picture to work and also sends me a text message on my cell phone. The text message is especially nice because it allows me to sprint to my PC and pull up the viewnetcam.com website and see what's happening real time at the house.
Thanks for letting me go on.....