Pin 1 is permanently connected to battery 12V (it maintains the memory of settings and preset stations. The set will forget any presets if this is disconnected or switched off)
Pin 2 and pin 6 go to battery negative
Pin3 goes to battery 12V. In your car this would be via the ignition switch so the radio would shut off when you switched off the ignition.
Pin 4 is the feed that powers dashboard lights. Connect to battery 12V.
The speaker connections should be the "right way round". Check your speakers: there might be a + and - mark, or different size terminals or a blob of paint on one and none on t'other. The speakers will work if connected the wrong way round but the audio "image" might be a bit weird. Start by trying all even numbered speaker terminals to the +, or red dotted or big speaker terminal.
Dunno about Aux. Dunno about the other small plug. Probably phone input plus phone control to mute the radio, parking aid muting, and various other stuff.