Harmonics for different instruments

I think most sounds are derived from actual captures, but I will leave others who are much better informed about soundfonts to answer that one.

Regarding "Are there details that describe the harmonics / amplitudes required to make a trumpet sound - trombone sound - clarinet sound - etc.?" The way harmonics interact to produce an instrument's sound is very complex. It can be different for different notes and can change during the attack and decay phases and, particularly for wind instruments can be influenced by a player's technique. A good book on the subject is "Fundamentals of Musical Acoustics" by Arthur H. Benade. If you take a look at that you will see how complex the subject really is.