New Englanders predominantly used smoothbores. While they had some Brown Bess (and especially some of the older ones), they had a lot of fowlers (much lighter and easier to carry than the Bess). I don't think any of them would have had an Indian Trade Gun as it was a lower grade firearm. As you surmised, the fowler's performance would be about equal to that of the Bess or Charleville but the latter two had one advantage: bayonet. There were a few rifles in New England, but smoothbores were the preferred arm (remember, they were there for hunting).
Rifles were also used and George Shumway's
Rifles of Colonial America Vol 1 & Vol 2 are both excellent books. They were out of print for years and were going for the hundreds when available. Happily Mr. Shumway decided to reprint them and you can get them from him at
http://www.shumwaypublisher.com He's highly regarded in the community (but has been fooled at least once by modern gun builders - hey, absent carbon dating/chemical analysis, you can't tell). Oh, getting back to the rifles, as one moved further south (Pennsylvania, Maryland, Virginia, the Carolinas & Georgia) rifles became more predominant. None of these were standardized and it all depends on what the gunsmith's skills were, his training (school) and the buyer's pocketbook.
The British fielded two types of rifles. The Pattern 1776 and temporarily the Ferguson. For info on both, DeWitt Bailey's book,
The British Military Flintlock Rifle is well researched and deserves a place on the shelf of any Revolutionary War buff.
The various German principalities (Hesse, Ansbach, Brunswick, etc.) but collectively called "Hessians" whether they were from Hesse or not brought their own rifles so the patterns may vary. West Point has one or two in their collection.
A couple of more books worthwhile looking at (and you can probably get them through your inter-library loan service) is George Neuman's
Battle Weapons of the American Revolution and his
Collector's Illustrated Encyclopedia of the American Revolution. Both are good picture books.
So, are you taking the King's Shilling, joining the Sons of Liberty or going Dutch Quaker and sitting it out?