The silver box was put there to house the electric window & door mirror switches. I had to have them moved because I drive my Vito from a wheelchair and couldn't reach them where they were. The box looks really crap though, so I intend getting rid of it.
The speakers in the doors are by a company called In-Phase, and the ones in the headlining in the back are Clarion. To my knowledge there were no major problems when installing the front speakers in the doors, although I didn't do it myself I had it done by a company. I've included the link to In-Phase for you. IN PHASE / INPHASE AUDIO