Well, the link below will take you to the tactics thread for sisters. We're a small group so pretty much all tactics etc are on that thread. Also, the new codex is only available as a digital download, the plus side is you can have it in a couple minutes instead of having to go to a store.
http://www.dakkadakka.com/dakkaforum/posts/list/558526.page
And for your army, you could run:
HQ
Celestine
Jacobus (the guy with the shotgun I think is Jacobus)
FA
Seraphim
Dominions in the immolater (take the melta guns and a couple girls with bolters)
Troops
15-20 girls with Jacobus (giving them a 5+ invul if he is your warlord), then a couple extra weapons for fun (maybe a heavy flamer or heavy bolter and a flamer plus a simulacrum imperialis)
10+ girls with the extra priest and some weapons (he'll make them fearless)
Tactically, you could outflank or scout the Dominions in the immolater, use the small squad with a multi melta or heavy bolter to guard your back field objective, use celestine alone or with the seraphim to wreak havoc, while the big sister squad with Jacobus can move upfield for other objectives and fun.