I went a couple of years back and it's well worth it. It's a good craic, as they say over there!
Can't really advise on ferry or accomodation cos I was in my appartment in Dublin and just popped up north for the weekend. Stayed in Belfast over night which isn't very local to the racing but sure was an experience.
There's loads of info as well as accommodation guide on the irish road racing website
http://www.irishroadracing.co.uk/nw200/nw200.htm Loads of really nice riding on the north coast to savour too... don't just talk about it chris, you'll love it.