<<<<<What size hardware cloth?
I bought some 1/4 inch mesh, and have not tried it yet.>>>>>
Quarter inch is suitable for winter use.  Three eighths gives plenty of
room for queens and drones so could be left on all year and will keep out 
all but an anorexic mouse.  Half inch would not keep out our small English
mice.
Appliance firms in England offer strips of  aluminium drilled with a line 
of holes diameter three eighths.  This strip is flexible and is easily
pinned to any entrance.
<<<<<Properly cured honey will last forever.  I suspect that the super you
stored was not fully capped and therefore not fully cured.>>>>>>>
The first sentence is true but only if the honey is completely sealed or
kept at a very low temperature.  Honey in comb is not completely sealed
even if fully capped.  In time moisture from the atmosphere will penetrate
the cappings and given the right temperature  fermentation will commence.  
The only safe place for combs you wish to store is the deep freeze where
yeast cells cannot function.  It's too late now but for anyone else in this
predicament I would suggest uncapping the combs and rinsing them well under
running water to wash off as much alcohol and vinegar as possible and then
giving them back to the colony late in the day  to clean up.  Never put out
combs of honey for all and sundry to clean up.  This is an ideal way to
spread disease and start robbing.       Sid P.