Button quail would not have died from meal worms unless you were feeding them so many that they got fat and died of a heart attack. That is very unlikely. As a general rule, though, treats should not be more than 10% of their diet.
Give them plenty of space, plenty of places to hide, and they're going to be pretty happy. They are originally from southeast Asia, so they don't take to very cold temperatures very well. I would not keep them outside below 60 degrees, but they can probably survive down to 50 well enough if they have shelter.