In doing some research for something else I saw this newspaper advertisement in the Boston Gazette, April 4, 1774
Messi'rs Morgan and Stieglitz
Request Permission to inform the Ladies and Gentlemen of Boston, that, having received assurance of the Patronage and assistance of the Musical Gentlemen, they purpose having at Concert-Hall, on Wednesday the 20th of April, a Grand Concert of Vocal and Instrumental Music assisted by the Band of the 64th Regiment.
The various bits of the concert are then listed. So my questions:
1.) I'm assuming the overtures in each Act of the concert are the full Stamitz symphonies (IIRC they're something like 10 or 11 minutes long each, but it's been awhile since I've listened to them)? Or were overtures shorter in the 18th century then what I'm thinking of (based on overtures from movies from the 50s, 60s, etc.).
2.) What is a German flute? Is it just a standard flute or something more like an oboe or a clarinet?
3.) The Harpischord concerto--any wild guesses as to what might have been available and played by a resident of Boston in 1774? Maybe Handel?
4.) I'm assuming that the Artaxerexes mentioned here is the opera by Thomas Arne?
5.) Hunting Song--is this a particular genre of music, or a song just named "Hunting song", or a song actually used on hunts?
6.) Any wild ideas about what kind of music might be played at a concert by a solo violinist in late 18th century America?
It's just the name for a transverse flute - what we consider a flute today. The term is used to differentiate it from an oboe or recorder.
Handel, Bach, Vivaldi - not sure what was popular, but there is a ton of Baroque harpsichord material from the time.
It's not a genre, but songs that were inspired by hunting were a popular motif for centuries. It wouldn't be a song used while hunting (having a great image of carrying a band around with you on horseback at a full gallop), but more a merry carousing tune at a brisk pace that sounds like a group out hunting.
The Bach sonatas and partitas would be a good choice. http://imslp.org/wiki/6_Violin_Sonatas_and_Partitas,BWV_1001-1006(Bach,_Johann_Sebastian), but I know very little about what would have made it to the US by that time.
This looks like some fun research! The Artaserse mention is very interesting! I think your assumption that it is the Arne setting is very safe, I guess technically any of the other million settings COULD have made the jump over the pond from Europe, but I can't think of any reason why they would.
Have you had any luck finding out who the "Musical Gentlemen" are? That might be one tack to come at this to find out what they might have played - sometimes Wills contain lists of music in someone's estate, or sometimes they show up in libraries as the So and So Collection. Otherwise some of the most commonly printed and sold sheet music in England for the 1760s-1770s would be the safest guesses, unless you can identify the Musical Gentlemen having some major collectors in them who'd have unusual hand-copied pieces. I'd bet $40 those early English Americans smacked out some Handel on the harpsichord for that party though, just as a matter of national pride.
Edit: /u/flotiste also did a big post on the German flute you should read.