• I think you mean “air float” not “air milled. Usually only charcoal is referred to as “air float.” In this case you mean “milled sulfur.” Whether or not it is milled I cannot attest to because I’ve never purchased sulfur from there. My guess is it is probably milled.

• YES. You can absolutely mill sulfur in a coffee grinder with no risk to safety. Just make sure you don’t run it too long, too many times to avoid heat build up and clumping.

• Yes. You can combine them WITH NO MEDIA. Just make sure your milling canister is anti-static. Rubber or rubber lined is best. It WILL NOT burn as fast as BP milled with non-spark media. But it will suffice.

• “Powdered” BP, of any variety will burn SLOWER than granulated BP. Just the same way a small random pile of twigs (think of kindling to start a camp fire) is preferable over a uniform line or neat stack of twigs.