The MP56 is just like the MP66 that I installed a couple of weeks ago, so here is what I know...

The USB and AUX ports are on the back of the unit. If the cables do not come with the unit you buy, they can be purchased as accessories. There is an SD card slot in the front behind the removable face. This can be used for mp3 or wmv files, or bmp files with the MP66 (not sure about the the MP56).

Blaupunkt are "plug and play" with our harnesses, as long as socket A pin 3 (telephone mute) is not used. My install took about 10 minutes, and most of that was running the USB socket to the map holder in the passenger foot well.

As far as performance... it made an AMAZING difference. I already had bass blockers in the doors to isolate the rear "subs" and clean up the mid-range. I was fairly happy with that, but was toying with adding a sub. Immediately after installing the MP66, I changed my mind. The sound is awesome. And being able to load large archives of music onto a flash drive and search on the head units screen is great. I do believe that the difference in displays between the MP56 and 66 will make searching large archives a little more cumbersome.

Hope this helps.