What Zfiend said, this game really is about the scenario so even if your basic plan is to kick face, scenario should still be an option and lady J is a mean assassin..... Both Sebastian and McMourning need to be close to the front line to get off their poison combos well, and remember the nurses poison+4 can help get some expunge action going as well.
When summoning models only the models rarity counts so say a model is rare 2 that means only two can be in your crew at a time, bought or summoned doesn't matter. Guild autopsies are not rare if memory serves so you can have any number of them on the board summon away!