> Beekeper extracts almost all bee and replaces it with sugar
If you mean that the larvae combs are removed and replaced by sugar... most probably not. The idea is having as much bees by beehive as you can breed.
If you mean that beekeepers remove "almost all" honey leaving bees to starve, this is an oversimplification. Any professional beekeeper know that will need to leave enough honey for winter. Leaving a minimum of 12-15 Kg of honey is standard and should suffice for the bees. If the beehive looks weak may not be harvested at all. Sugar is provided if needed as winter emergency feeding. The beekeeper will feed the bees in autumn also to assure that the fall born bees are as strong as fatty as possible.
> If you mean that the larvae combs are removed and replaced by sugar... most probably not. The idea is having as much bees by beehive as you can breed.
GP almost certainly meant that beekeepers take all the honey then they feed the bees sugar-water. That actually is true of some (many?) beekeepers.
It depends strongly on location. Winter bees live on autumn fat. If the bees are well feed in fall and the winters are warm, will need much less honey to survive. The beehive will not be required to be warmed against chilling temperatures for example so bees don't need to spend so much energy warming it
Not I! Sugar water is terrible for the bees. If you want strong colonies that over-winter fine and bounce back fast in the Spring to make lots of honey, then you'd best leave them plenty of honey to make it through the winter. I only extract half of what I harvest (freezing that which I don't extract so I can give it back later if the colonies need it), and I leave a fair bit in the hives too.
Don't buy commercial honey. Buy local, small- and medium-batch honey.
Edited typo