Once the water temp gets below 10 cease to feed as the fish can't digest food at temps this low.
Dont start to feed again until you are sure that the water temp will rise above 10 for an extended period of time, like spring and summer. Your fish will go into a semi comatose state during the winter and should have built up enough fat reserves to see them through until the temperatures start to rise again.
Wheat based food is easier for your fish to digest, but I would personaly refrain from feeding anything.
As for your filter, its up to you. I leave mine running all year and just give it a good clean out before the real winter kicks when the bio load drops, (when the fish have stopped feeding and you have removed all dead plant matter). If you can, lift the pump off the base of the pond, as this is where the warmer water will sit and your fish will call home for the colder months. Always clean your filter media in water from the pond and not the tap.
Dont worry to much about your filter frezzing as running and moving water needs very low temps before it will frezze, (below -20 i think, dont quote me on that!)
How ever if you wish to turn of pumps and drain your filter once the water temp drops I can see no harm in that either as the bio load will drop off to almost nothing once the fishes last meal has passed through and has been dealt with. although you will needto make sure all pipe work is fairly well empty as stationary water does frezze.
Like I said I keep my pump and filter running, as even in the coldest weather we are likely to see, the running water will keep at least part of the pond surface un-frozen, (assuming the water is returned via a water fall), which will help in gas exchange at the surface and keep oxygen levels up.
If you do switch off and the pond frezzes, defrost a hole using saucepan filled with hot water sitting on the ice to melt a hole.Dont hit the ice to break it or pour hot water on to it as the shock waves can disturb fish that are already on a low par.
Either way,filter on or off, when the weather starts to warm up and you think its time to start to feeding again its agood idea to add some bactreria to your filter to give a kick start, (any of the filter start sachets that are available in good out lets will do the trick, and dont add any new fish ubtil the filter has a chance to build up its bacteria culture again.
hope that helps,
Dont knock on Deaths door! Ring the bell and run away! Death hates that!
bypass the water fall, i use a long piece of pipe so the water goes through that and onto the pond surface, turn off the fountain or just havve it circulateing the water rather than squirting it out the surface
raise pumps as said, i leave my filter running but wwe turn the UV off as it's not needed so save eleccy
clean it out as above says so the crap is gone
when feeding in spring, feed spareingly and everyother day for a week then daily for a week then slowly build up the amount you feed each week till your feeding like you would like to at a later date, make sure it's still wheatgerm so they get what they can out of it while it's still chilly, then switch to your summer food when it's nice and warm
There are no experts, mearly beginners who know more than others.
Support your LFS, online sites won't stay open 5 mins extra for you