I wanna help too! Sorry, don't mean to butt in but I enjoy talking about roaches just as much as Jeff does.

What is the absolute low end to have either species breed, runners and Dubia? At what temp do they die both high and low?
I can only speak for Dubia. I'd keep it around 90-95 to guarantee consistent breeding, but they can breed more slowly in the 85 degree range. They won't start dying until you get below the 45 degree range, but are pretty sluggish and probably don't eat very well at temps that low.

The heat source, is it meant to keep the entire colony at 85-90 or just the egg crates where they stay? Can the food and water area be slightly cooler or will the heat mat/tape keep the whole bin pretty much the same temp?
You should still have a cool side, although technically if they get too warm you we see them chilling out at the tops of the crates, which is fine. My setup has the food/water on the cool side, which is what I recommend. Warm side should be the crate side.

What temperature do you keep you colonies Jeff? And how many adult runners or Dubia would I need to have approximately 400-500 nymphs a month to feed to my frogs?
i hope I can answer too. I keep mine between 90-95, usually closer to 90 degrees. I've heard that temps above 95 degrees can kill adult males, but haven't personally experienced this because my heat pad doesn't get that hot. Growth-wise, each female will give birth to 20-30 babies each month.

I would recommend the 2-bin setup, it's what I use. That way you can feed your breeders higher protein stuff, and your feeders the stuff your frog would benefit from. I have a bearded dragon and pacman, so I feed my feeders collard/mustard/turnip greens, prickly pears, and very rarely fruits like apples and mangos. I feed my breeder colony a roach chow I make myself that includes dog food and plant proteins. I recommend feeding them more than just fruits and veggies, otherwise the males will kill each other. I have experienced this with my colony when I just gave them fruits/veggies when I had only one bin and fed directly from my colony. Having two bins also has the advantage of not needing to bother your feeders too often, which believe me the less you mess with them the more effectively they will grow.