If the 80 is working on Friday it will almost certainly work that diagram. It can only work diagrams that start and end in Belfast (no Larne overnights), so that's the one. 450s have more life in them yet, so if you don't get any 80 class action you'll still have a great day. Reliability being what it is nothing is guaranteed, but NIR are so short of sets that anything gets pressed into service.
Yorkgate is the nearest station to the docks. It's about a 40 minute walk from the ferry terminal (bring a map!). If the boat's on time you will be able to pick up the 07:29 Central > Larne Harbour at Yorkgate (450 class) out as far as Greenisland and take the 07:30 Whitehead > Central back in from there for a bit more DEMU action (and a lot less hanging about at Yorkgate, surely the ugliest location on the Irish railway system).
Yorkgate is the nearest station to the docks. It's about a 40 minute walk from the ferry terminal (bring a map!). If the boat's on time you will be able to pick up the 07:29 Central > Larne Harbour at Yorkgate (450 class) out as far as Greenisland and take the 07:30 Whitehead > Central back in from there for a bit more DEMU action (and a lot less hanging about at Yorkgate, surely the ugliest location on the Irish railway system).