NotoriousBRK

Agree on the Raytec recommendation. Technically, you need two separate components for this: 1) A camera, lensed accordingly to give you the detail you require of the scene. 2) An illumination source (most likely IR) capable of providing sufficient illumination at the target. These are two separate devices, each with their own selection criteria. It's unlikely you'll find one device that fulfills both needs properly. If at all possible, I would try to place the IR illuminators as close to the playground as possible. Since they just need power and not network, you may have more flexibility than with the camera side of the equation.

Do you have a higher-res satellite pic? Also, how wide is your roof (or some other reference point in the image)?

This device will technically do what you want: http://www.computermodules.com/broadcast-systems/ucm4540.shtml But the problem is the digital systems are way more complex than the old analog systems. Most of the cable boxes today need to be pre-authorized for each channel they receive and/or they also check with the head-end to make sure they are authorized to tune a particular channel. Also, with the older analog systems, each channel corresponded to particular frequency range. With digital cable and the QAM modulation, channel 399 isn't necessarily a specific frequency. So you need to know absolutely what frequency range is not being used by the cable system, notch that out of the main cable feed, modulate the camera signal, inject it, and then work with the cable co. to make sure the boxes know how/where to find your in-house channel. Your best bet would be to start by contacting the cable provider, they may be able to do this easier than you think, but I doubt you're going to be able to totally do it without some involvement from them.

Yes, but this is mostly a function of the PC Client software. Also remember that to zoom in digitally you need to be streaming a good image from the camera to the PC in the first place. On a LAN this is usually of little concern. But if the attendant is connecting to the lot camera via WAN, then you may have issues with adequate bandwidth.

RemoteReality.com was working on something like that a few years ago. Haven't heard much from them in a while, not sure what's going on with it.