Regarding the Mannheim style, I found an interesting quote from Mozart taken from a letter to his father. (I quote it from the first book I mentioned in my first post.)
You cannot imagine the glorious effect of a symphony with flutes, oboes and clarinets.
At a time when we take the things for granted, it's amazing to know that there was a period (when Mozart was still alive) when this was all new and revolutionary. I can't imagine listening to the late works of Mozart without some of these wonderful woodwinds.
Yes, Mozart was bowled over by the Mannheim band. It started a whole new line of thinking for him. Their particular idiom involved some novel ideas, like actually playing together...
But it's true, before them, an orchestra was primarily the string section that we would call it today. When Mozart returned from Paris, he lobbied the Archbishop long and hard for clarinets for the orchestra in Salzburg, but to no avail. He had to remove the clarinet parts from the Paris symphony, for example, and he (probably) never bothered to rewrite the Sinfonia Concertante for Winds to include a different solo part from the clarinet that it was written for in Paris. But he did continue to use some Mannheim standard devices, like the "Mannheim Rocket" which the French called the premiére coup d'archet
. It shows up in several of his later works, and still pleases today.