Karen,
Regarding ventilation:  I cut an upper entrance, 3/8" tall X 1 1/2" wide, in
the front edge of the inner cover, so that bees can go in and out of the
colony via this entrance which is just under the front edge of the
telescoping cover when the cover is pushed forward as far as it will go and
this leaves a space about 1/2" wide between the inside edge of the cover and
the outside face of the hive body.
Only foraging bees use it and they "sort of" have to learn that it is there.

It is MUCH MORE INTERESTING to me that the great majority of beekeepers do NOT
have an upper entrance during the WINTER when it is so VERY IMPORTANT to get
the
damp air out of the hive that is created by the breathing of the bees.
Research has proven that temperature is not very important or deleterious to
a bee, but dampness
can easily chill bees.  Hence, all my colonies have an upper entrance as
described above on a hive 365 days of the year.

Although my area (near Washington, DC) rarely has snow or drifted snow deep
enough to cover the front entrance of a colony, if it happens, the bees
always have the upper entrance to use for cleansing flights and to keep the
bees from smothering.  Many years ago, we had a sleet storm that later froze
and sealed the bottom entrance and the bees smothered and died.  Mine did
not, because of the upper entrance.  However, this was quite unusual, but
DAMPNESS from bee breath is
ALWAYS present if there is no upper entrance, because the hot bee breath
rises to
the inner cover.

I hope I have helped.

George Imirie