Fat cap up or down?

When your fatcap is up, the juice (fat) penetrates/renders back down through the meat.

Between the meat and your heat source

Up indirect, down direct

Depends on where the heat is coming from. Always put fat cap between fire and meat.

Fat cannot penetrate and baste the meat like another poster stated.

Trim it down to about a quarter inch. Discard the fat. Put the brisket how ever you want.

Like others have said, it doesn't make much difference, but that pound and a half of fat adds an hour or more to your cook time.