I'm no expert - just a couple of thoughts - if I was placing the garage camera (assuming a bullet camera) I would put it just to the left of the downspout (if facing garage door) pointing towards the driveway. I'm not familiar with the hikvisions, but for the cameras I've used you can only rely on around 15-20 ft for IR coverage - if it was placed above your garage as indicated in your photo you would lose a lot of night coverage on the garage roof.
Regarding your door cam - I have a similar situation - I ended up putting the camera to the left of the door pointing down from the ceiling.
It's not the best of all situations, particularly when it comes to getting face shots, but it is better than nothing, and more importantly I get alerted via
Blue Iris if any motion is detected, which is at least half of the value of having cameras (my opinion).
I'm finding that although it would be great to position cameras at the best angles, I have to settle for a balance of home aesthetics and coverage. By placing multiple cameras around I get adequate notification of motion/activity -and- collectively, they provide pretty decent detail.
Take your time and choose the right places - I've even run temporary ethernet/power & mounted the camera just to see what the vantage is before I went to the trouble of running cables in some cases.
Good luck!