New Hikvision setup - focal length advice

Hi,

I am in the process of renovating my house and as an afterthought thought it would be wise to install ip cameras.

I've run cat6 cable to the locations shown below;

Although not ideal positioning, hopefully it should be able to cover the majority of the house perimeter.

From the picture above the house, the front 4 cameras would be facing towards to road and the back 2 towards the rear garden.

My current thinking is to purchase Hikvision DS-2CD2342WD-I turrent cameras for each location marked on the diagrams (6 cameras in total).

From my initial research I was planning to use 4mm focal length on all but the camera mounted in the porch area.

I had seen 2.8mm recommended for the porch area, but looking at comparisons shots it seems to make more sense to use a 6mm lense - as the rest of the front of the house should hopefully be covered by the other 3 cameras, and by using the 6mm I should hopefully be able to get a good look at anyone who approached the front door.

Does anyone see any issues with the above or can recommend better alternative options?

With regards to mounting, is there any reason to use a junction box or wall mount as opposed to just mounting directly on the exterior of the house?

I've attached some additional location pictures in the second post.

Thanks for your help

Additional pictures.