it's a bit primitive but the only real way to make sure it's not too frozen to drive if you need to get to work (..etc) is to leave it in gear with a brick or two under the wheels! very common problem with starlets, moisture in cable as you said 9/10 times, alough i'd never recommend using a lube on any part of the braking system! it can be costly to replace the cables, so most people just keep an eye one the weather anc choose option one!