walldaja

Good questions!

Cornets typically are a little darker sounding and more flexible--listen or look at the Clarke studies.

C trumpets seem to have a more delicate sound than a Bb. They also provide the ability to read off piano music without transposing. Being a shorter horn, they seem to slot better too.

Big difference between a pocket trumpet and a pic. First is the octave (pic is higher). The pic is often used to achieve a Baroque sound. A pocket trumpet is more of a gimick than a main line instrument. Most are quite out of tune. Don't presume a pic will give you the capability to play higher--generally you get pretty much the same range of actual notes from a Bb or a pic. They definately are a new skill to acquire.

The forth valve allows you to extend the range of the instrument, the fourth valve is essentially the same as using 1 & 3. I've never been able to convince my little finger to work independent of the third valve finger so I subscribe to the practice of using the first finger of my left hand.