Usually in the neighborhood of a cup Kosher per gallon. Be SURE to use KOSHER salt. Sounds like you'll need about a gallon to cover that anyway. Use Stainless, food grade plastic, or glass for brining, or even those mombo freezer ziplocks. make sure meat stays submerged in the brine..weight with a clean plate on top.
I also add some onion powder, ground rosemary, thyme and CBP. Might wanna toss in a half cup brown sugar if ya like a touch of sweet. I'd say a brine of 4-6 hours would be sufficient.
Cook to at least 145* <new rule!> in the center of the breast. As mentioned before, I go to about 170*. Cook at 250-350 range, higher end for crispy skin.
I MISTYPED!! Crap 165*!!!!