Bees eat honey and pollen, the honey is made from the nectar they collect, then stored in the honeycombs until it's needed, the pollen is also stored in the combs.
A good colony of bees will create much more honey than they would ever need for the winter, it is the care and attention of the beekeeper which makes them a good strong colony, so we look after the bees, in return they reward us with a good crop of honey. We also feed them a sugar syrup or a sugar paste in times when there is no natural nectar or when it's too cold for them to leave the hive.
The honey bee colony does not hibernate or die out over winter, it therefore needs food to survive the cold winter months when there are no flowers available, so they gather nectar and store it in honey combs for winter food.
Three, there is a single queen who is the only female in the hive to lay eggs, thousands of female workers and hundreds of male drones, these however are evicted and die in the autumn.
This varies massively from spring and summer to winter time, but summer is often around 50,000 where this can be as few as a couple of thousand by the time they are coming out of the winter.
Most workers will tent to fly fairly close to the ground, unless forced to fly higher, this is why many hives face a wall, fence or other barrier of some kind, as this forces them to fly higer up and therefore above people walking close by. Drones however will congregate for mating at heights of approximately 30 meters, even higher if caught in warm thermals.
There are several illnesses which can affect the honey bee in the UK, AFB and EFB (American/European Foul Brood) are amongst the most serious, once a colony is infected it's common practice for the entire colony to be destroyed and the hives burnt out on the inside. This may sound extreme, but if left it would only spread to other hives in the surrounding area and if left alone, the colony would die out anyway.
Pollen is stored and when used, mixed with water to create a paste which is fed to larvae in the brood box, this is the bees source of protein (carbohydrates are from the honey) It is said that a typical colony will collect around 20Kg of pollen each year, if you consider that they can only carry about 20Mg on each trip, this is approximately 1 million journeys.