Putting candy over your feed hole will not suffocate your bees i have a number of hives in that position and all are fine. A hive is in no way air tight. With regard to the snow check out Finskys pictures of hives in a foot deep snow tunnel!!!!!!!!!!. In fact if hives are covered it is recommended by most that you leave them that way. I normaly like to put the candy directly onto the tops of the frames above the cluster so the bees have direct contact.
Glass quilts (crown boards) are terrible things if you check a hive in the winter that has one, even if it's on a mesh floor condensation forms and it just rains cold water on the cluster all winter long. The biggest inviromental killer of bees in the UK is not the cold but damp!!!!!!!!!
With regards to using the euipment again check this out. http://www.bbka.org.uk/phpBB2/viewtopic.php?t=836
Hope this helps