MrsC - okayyyyyyyyyyyy....here's how it works!
A frequently feeding baby - like yours - orders up the amount of milk she needs, by removing the milk frequently :)
With only an hour or so between feeds, the breasts do not have time to over-fill. Breasts which feel soft may still have plenty of milk in them for the baby.
Over-full breasts - the ones that feel full and even hard - may not have loads more milk in than the soft, floppy variety, anyway. If you think of blowing up a beach ball, the difference between a ball with air in, but still soft, and the ball feeling hard can be as little as a mouthful of air.
As long as you feed responsively, when she wants, without restricting her, there is no reason on earth why you would run out of milk. Ever.
Hand eating and dribbling is what babies do, a lot. She may have started to have some control over this, and be able to 'direct' her hand to her mouth, which would explain why she is doing it more. The dribbling comes with the hand-eating....babies don't co-ordinate saliva swallowing that well, hence the drool :)
Babies change their feeding needs all the time, and they may often increase their needs when fighting an infection so you could be right about the cold.
Hope this helps :)