Thats a complete judgment call on how much to use.
As for how long, that would depend on how long you want to ensure a youthful blood system.
Actually more is better and hotter is better.
But any amount or heat is better than none at all.
Its whatever your comfortable with, whatever your body is comfortable with.
As for the heartburn, you'll just have to go lighter till you find whats comfortable.
Don't ever take it in capsule form.
When you drink it with juice or whatever liquid, hold it in the mouth for a second.
This prepares the stomach for its arrival.
If thrown down the hatch in a capsule, the capsule opens in the stomach and it can be like a bomb going off.
The stomach had no prior notice of its arrival and wasn't able to prepare.
Cayenne is also very good for the digestive tract.