A: At 80% RH your cigars are going to get mighty spongy. If the temp is almost as high, you risk mold or beetles, but more likely the former. For now, I would remove the humidifier, since at that level you probably don’t need it. Place the humidifier in a zip-lock bag and put it away until the weather turns colder. However, if you see the RH dip below 60%, replace it. Try to move the humidor to the coolest space in the house, too. Make sure you’re not refilling your humidifier too often, either.
Finally, yes, opening the lid and letting the cigars get some fresh air is good to do on a regular basis. Usually an hour a week will do it, though it may not have that much of an effect on the moisture already in the cigars. Try rotating your cigars every couple of months, too, to help keep things equalized.