I don't think I have any spoilers in here, just general game info surrounding the time limits and tactics.
I'm not really struggling to mix everything together and really enjoying the game. I don't think I've missed a survivor mission yet. And I've only had 1 survivor die (although I've had 2 XXX is dead, when I've not been near anyone), because he turned on me when I was killing zombies with my broad sword.
Basically, I wait for a new case file and go on a survivor hunt. You get new survivor missions when you get new case files, so I prioritise a survivor area and take along some shotties + rifles. Once I have my army of survivors I head to a psycho or two and none of them have caused me any problems while I have my army of helpers. Once the psychos are dead I head back, drop off the guys and go do the case.
Some survivors require a bit of special planning due to their inability to arm themselves, but I work around them. The shortcuts through the map are massively important. The zombrex hasnt been an issue either, and I've treated survivors with it, with more to spare for Katie. Might have to buy a dose next, but usually the storyline seems to give you some just when you need it.