Yes, the air can leak out of the crack.
yes it will
Maybe a mile or 2 to get you to a place you can get a spare. Driving on a flat tire can cause damage to the wheel and possibly the drum and brakes. If you must drive on a flat tire, drive very slow and stop if the tire comes off the rim.
A slanted tire is a serious safety hazard. It can mean the tread is separated or the wheel housing is cracked. Either can cause a potential accident. It is best to either change the tire, or get it checked.
If you suspect a flat spot on a tire examine the tire closely. You should be able to see a flat spot. To determine if your car has a bad wheel bearing rotate the wheel. A bad wheel bearing will often make a grinding sound as well as feeling rough as you turn the wheel. A bad wheel bearing may also shake or wiggle. It will also cause a car shaking problem.
A flat tire is one possibility
You will destroy the tire and harm the bead seating surface on the wheel.
no, overnight rain will not cause your tires to go flat
A bad wheel bearing can cause your tire to tilt inward. The motion of the tire tilt thing in word, while you are driving, can cause the axle to break and the tire to come off.
Usually the problem with a wheel barrow tire is the wheel rather than the tire. That is a poor fit between the rim and the tire. You need to take a strap and tighten it down around the outside of the tire and then inflate the tire so that it grips the rim tightly.
If it is part of the valve stem, yes.
Only if the valve stem is bad.
You need a jack and a wheel brace (wrench)