Yeeees!
It is indeed Herr Mozart. Although he is pictured as composing his last play...Requiem.
Although the picture may not be quite true as studies that have been made seam to agree that Herr Mozart was in good health when composing the finished parts of the Requiem.
Regarding Streiff, I have seen him at the Royal Swedish Armory in the castle in Stockholm, it is also the place where King Karl XII's Uniform, gloves, and tricorn that he wore when he was killed in 1718. Quite a great museum, I have some 200 pictures from this museum that I will upload on a future website of mine

Its your turn Julian!