As someone who's had CCTV for years and got one conviction for an attempted burglary years ago out of the footage - CCTV can be put up by anyone and almost any kit used - whether the footage when needed is any good for a conviction is an entirely different matter.
With the analogue systems - multiple cameras, some zoomed in to cover points where a face\torso will pass, required far more cameras and not cheap lenses.
With the prices of IP cameras having dropped substantially and 4MP and 8MP becoming a lot cheaper, a lot can be done with fewer cameras.
I've recently swapped to a HD IP camera setup. I have a 4MP camera looking down my drive and I can zoom in and read number plates of cars that turn round in front of the house - 4 car lengths away.
The rear garden is much bigger, so have an 8MP camera there - and zooming in 8 times faces are recognizable 25m at the rear fence.
Placing them at the eaves, will only get you the top of someone's head. They really need to be placed no more than 8 feet from the ground to see a face. I suggest you stand on a ladder at the height you're thinking of fitting one and have someone walk around and you'll experience first hand the field of view the camera will give you. Better still make a funnel out of a sheet of paper and look thru the small end - more realistic.
I spend a fair amount of time researching cameras - and the best quality\value for money proposition I came across was the following,
https://www.youtube.com/watch?v=8DpMRXvG1Cg
I have that at the rear. At the front, as the field of view I am interesting in monitoring isn't as far, I bought the 4MP version -
https://www.youtube.com/watch?v=sAjvERvUUmI
The quality of what my cameras record is identical to what the youtube videos show.
I ran Cat5 cable - power and data all in one. But that's with me having a Hikvision NVR (network video recorder) which has network ports that supply power too (POE).
Cameras and NVR (which isn't strictly required) were a doddle to set up.
HIH
Dibs