Adding Usb Outlets

I would like to add some Usb outlets to my car, a Mk2 Octavia.

Simple thinking says take power from the fuse board, run to a distribution box and then run power to where's needed.

I want to add 4 to the car, 2 up front and 2 at the rear, that'll allow my tablet and phone to be charged and my boy's tablet and wife's phone to charget too. I have the modules en route and will be 2x dual outlet from a single tranformer. Rears will be mounted on the side of the console, 1 front will in the top dash compartment and the other in the facia adaptor for my headunit.

Would this be the best way of doing it? If so:

What size fuse would I need?

What distribution block? I wouldn't have thought crimping together would be the best way?