re: Edinburgh restaurants

Looking at the Stena Line site, you can't take a ferry from Dublin to Cairnryan (coastal town in Scotland), you can only ferry from Dublin to Holyhead in Wales.

So you'd have to take a train to Belfast, hop on the ferry, get on a bus to basically Glasgow and rent a car to drive to Edinburgh.

You're better off flying both ways if you must see Edinburgh. We only spent a day there and it was cool to see, but lots of tourists. I enjoyed Scottish highlands and isles (Oban, Skye, Inverness is where we stayed overnights) significantly more than Belfast or Edinburgh. But a two day jaunt to the highlands would be a whirlwind mess itself.