Re: top venting.
I know I have mentioned it before, but I use a 3/4" hole bored about 4" down from the top. By this time of year the bees are in the top box and the bottom entrance could be covered with snow (not this week).
So, I think this gives them an entrance close to where they are living, allows them to come out if it's sunny, and possibly aids in air circulation. I doubt it hurts anything.
PLB
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