I've run trips up there for the past 5 years. I used to go to a lodge called Dhoon Lodge located outside of Stephenville. Newfoundland is an absolutely beautiful place with great rivers and fishing. Most of the fishing we did was from Deer Lake to Port-aux-Basques, specifically the Bay St. George area of SW Newfoundland. There are at least 10 very notable salmon rivers including the Harry's River, Codroy, Crabbes, Robinsons, Flat Bay, South West Brook, Serpentine, Fox Island, Lower Humber, Upper Humber, etc. Above Deer Lake (northern penninsula) there are many more rivers (I haven't fished them - yet).
You will need a guide as an outsider. If you go and need a guide I may be able to help you depending upon where you're going to be in Newfoundland. You can email me if you have questions [email protected]
For flies you'll need sizes 6(large for newfoundland) to size 12 and they must be single hook/barbless. For patterns I would have some very simple sparse patterns. Some good patterns would include Black bear green butt, undertaker, blue charm, black silver tip, bondatti killer, colburn, cosseboom (in different colors), silver rat, grizzly king, etc etc. Most of your standard salmon flies will work, only in smaller sizes then what you may think. When in doubt, go small.
Most of the rivers, unless you're fishing Humber, Gander, or Exploits, are medium in size. Harry's River and Codroy are pretty large as well. Single handed rods in 7-9 weight or smaller spey rods from 12.5 - 14' 6-9 weights are ideal. All floating line fishing as most of the rivers are shallow and run on the warmer side, especially during the summer months. In terms of size of fish, I know Newfoundland has a reputation as being a grilse area, but we've caught many nice salmon in the 8-18 pound range with fish to 25+. Certain rivers definately have more girlse than salmon. Some rivers may be exclusively grilse rivers, but there are many rivers to choose from, especially if there is good water. Low water will limit options.
In terms of cost, the trips I ran for 6 days of fishing were approx 2000 for lodging, meals and guided fishing. If you DIY with a guide I would expect room rates from 40-100 per night and you could probably find a guide for 75-150 a day. You could definately fish there fairly cheap, but a guide is a requirement. In terms of getting there you'll have to fly through probably a combination of Halifax, Montreal and/or Toronto. Air Canada has flights. If you have miles with American Express you should be able to transfer them to an Aeroplan account which works with Air Canada. You would probably have to be flexible though. I just booked a flight for September to Terrace BC for 25,000 miles from NYC. Just had to pay the taxes ($150).
Hope you have a good trip and if you need any help please let me know.