Size of screw\nut

[nigwhyrito]

Starting my first project - adding a hd radio.
need the nut size and ring terminal size of the power distribution block in the back of the x5 underneath the tire.. a little plastic box.
There are 2 nuts on mine missing the one for the 50AMP and 100 amp.

Also the size of the nut or ring terminal to use on the big black ground screw right next to it.

Where is the closest place to pull ACC from in that vicinity.. NO NAV,NO cd changer, just mid and BMW rear seat entertainment.

And finally please dont laugh when you disconnect the battery for projects.. Do you normally disconnect the actual - lead on battery or do you just disconnect the big black wire ground lead near distro block, Or just disconnect the fuses ya will need. I think its 2 for audio 1 up front and 1 in rear.