sounds very similar to what was in mine when I got it. It had a full multi media unit by Sony - DVD, CD, Sat Nav and TV - the CD worked fine, the DVD would have only played DVD's from Japan and the sat nav worked fine as long as you wanted to drive around Japan. I took the whole lot out and put an alpine ipod unit in.
You need a nissan micra harness - i got mine off ebay - don't bother with halfords - even the universal Nissan one was no good. If you do a search on here you'll find the correct code etc - I don't remember it off the top of my head.