Re: Jazz sound
When you're playing, don't blow air through the horn like you would normally. When you blow normal, you're producing cold air, so just sort of exhale, and when you need to get loud, blow from your stomach and the bottom of your lungs, not the top. You can test this by blowing on your hand.
Also, you need an open throat at all times in jazz. Not only does your throat need to be open, but in jazz your mouth should be more open inside than in classical. I'm not sure how developed of and eoumbechre you have, but you need to know what you need to change for jazz.
Definetly get rid of the Rovner Dark. Cloth ligs like that don't give any vertical pressure, and it's just going to be a mess. Try the Francois Louis. If that's a little expensive, then try a Bonade invert lig, they're really good for the price.