I don't play with picks, but I've spent lots of time with great players who do. If they're any indication, thumbpicks are for going down. That's it....
Just like anything else that's fragile and requires care when handling. Don't leave it in the sun or in the car. Otherwise, nothing special. Humidity...
Which is pretty darn cold on any temperature scale... The coldest temperature I ever experienced was minus -46 degrees below zero Fahrenheit. It was...