For the Newfoundland meaning of the Two Sunkers and other terms, I refer you to the excellent Dictionary of Newfoundland English

Some of the uncommon terms in "We'll rant and we'll roar (The Ryans and the Pittmans)" are:
Standing room: compartment between the thwarts of an undecked fishing boat
Sunker: A submerged rock over which the sea breaks
Chokey: Jail
Frankgum: also Frankum, the gum of the spruce tree, used as chewing gum
Case-pipe: meerschaum pipe, named from the protective case enclosing it
Settle: A long, home-made wooden bench with arms and high back, or an unupholstered couch.
Two pound ten: British currency. Until 1949 when it joined Canada, Newfoundland was British territory. In fact, Canadian servicemen who served in Newfoundland during the wars were considered to have done "overseas service." Newfoundland adopted the Newfoundland Dollar to replace the pound in 1865.

The place-names in the song are all located in or near Placentia Bay. Many of them were abandoned in the Smallwood government's resettlement plans of the 1950s:
Toslow: A fishing community on Placentia Bay
Valen: Properly, Isle of Valen, a community on Placentia Bay (now abandoned)
Oderin: Oderin Island in Placentia Bay (now abandoned)
Presque: A small community on Placentia Bay (now abandoned)
Fox Hole: No town by that name, but there is a Fox Harbour on the Avalon Peninsula and a Fox Cove on the Burin Peninsula, both of which are adjacent to Placentia Bay. There is also a Fox Island Harbour (now abandoned) on Fox Island, at the end of the Burin Peninsula.
Brule: The town of Great Brule, on Merasheen Island in Placentia Bay (now abandoned)
Crabbe's Hole: No town with this spelling, but there was a community of Crabb's Hole in Placentia Bay (now abandoned)
St. Kyrans: a community on Placentia Bay (now abandoned) near Presque
Paradise: a town on the Avalon Peninsula
Big Bona: probably Great Bona on Placentia Bay (now abandoned)
Little Bona: A town on Placentia Bay (now abandoned)
wall with the hole in: Possibly the narrow entrance to Toslow Cove