5 nights in Moville seems like a lot, though the Inishowen Peninsula is amazing.(as are all the peninsulas in Northern Donegal along the Wild Atlantic Way between Horn Head in Dunfanaghy, the Atlantic Drive near Downings and the area around Portsalon)
I'm a fan of Greencastle GC.
Given you ONLY have two nights in Buncrana, you've made great choices in Northwest GC and Buncrana GC.
If you can squeeze an extra day in/around Buncrana or get an early start, the drive to Portsalon is spectacular from Moville-it's not that much farther than Buncrana.
You could play Portsalon or 9 hole Otway, which is really compact and cool, though Clyde Johnson tells me it has had a few altered for the worse.
You could then take the Rathmullen ferry into Buncrana, which operates in June(I think)
Buncrana is a fun town though.
To your question about the drive to Dublin, Slieve League is NOT on your way, BUT I would highly recommend it, especially on a nongolf trip.
If you're looking for a golf diversion, Layton and Bettystown would seem a natural pre Dublin stop