Reddit reviews Insulated Lunch Cooler Bag, Black

I carry them around in something like this with no issue: http://www.amazon.com/Insulated-Lunch-Cooler-Bag-Black/dp/B000IBH0BS

They're incredibly sturdy. I've dropped one from chest height onto tile floor with no damage. My dog was able to chew up one of the lids, though.

As for dividers, it's hard to imagine an effective one that's not plastic or metal. Don't have any good suggestions here.

Cheap insulated bag from Amazon and keep it out of sunlight?

This is a cheap (big) one.