Not really to the former, absolutely to the latter. But if you're using PK, are you sure you have room on the team for FB?

I have only Draco with FB.  Do I use one of the speed tune tools that are online?

Will more def on each champ help them stay alive longer?

Not really matter your resists.

Second, i think you not need FB with Draco. Draco can fullfill his poison the CB debug slots with 8 poison and dont forget the weakening and def down.

Change FB to something else. Def up champ/healer or other damage dealer.

I have FB because of her 25% poison sensitivity.   She magnifies the damage from Draco poison

No matter. If you want to use it there, use. But there is much better solutions over a simple 25% poison sensivity. Def up champions for more survival, Counter attack champions for more damages, big hitters, block debuffers etc etc etc.