my snpa clone is
10lbs 2 row
1 lb crystal 60
.5oz mag 60 min
.5oz perle 30 min
1oz cascade 10 min
2oz cascade flameout (i like to add it at 180f)
ive dry hopped this recipe with citra/amarillo aswell.
on the question of using pellets to dry hop. I would do it in a secondary and not your keg...