I think the thought behind "two cables" is that if one dies a few years down the road, you've got a backup ready to go... It can be more expensive to try and fish a second one later than just have strung a second one during the build.
Wiring for porch cameras was a good call, because like
@SouthernYankee mentioned, cameras on the corners of the houses are great for getting a general overview of what's going on, but you're not likely to ID anyone from one of those. The cameras on your porches should be able to ID folks.
If you ever do any work on your house later down the road, consider running some ethernet down to the sides of your garages looking at your cars.
The most popular cameras here for outside are Dahua Starlights. For general purpose (like your house corners), the varifocal turrets (like the 5231 or 2231) are probably the most commonly used. A model used on porches a bit is the 4231 wedge. Spend an evening or two going through the Dahua forum here, most popular cameras have big review/owners threads where you can learn a ridiculous amount of information.
Most folks order their Dahua stuff from a trusted vendor on here named Andy --
@EMPIRETECANDY. He's got his own forum in the vendor area.
The other thing that often tough for folks to wrap their heads around when first learning more about these cameras is that if low-light image quality (i.e. from dusk-to-dawn) is important to you, the best cameras for that are still really 2MP... specifically, Dahua Starlight or Hikvision Ultra-Low Light models. You're going to see 4MP/6MP/4K <8MP> cameras that all claim to have great "night vision", but the only ones that beat the 2MP Starlight/Ultra-Low light models are 2x-3x the cost. A lot of these common higher MP cameras will have marketing pictures of great looking night shots. Remember that it's relatively easy to get a great looking night shot from a camera when nothing's moving, .. the hard part is getting good looking video (i.e. minimal blur) when something is moving at night.