Find out where the pipe is frozen and getting some heat tape on it. Probably close to where it comes into the house.
Cold water.
Cold water lines may have more insulation than hot water lines, otherwise they should both freeze unless there is some agent in the water.
Both.
cold water and water at night dont water when the sud is out
Celery can grow in both hot and cold water, It helps only slightly for plants to grow in warmer water.
Assuming that you tuned the faucet to hot and let it run until the hot water should have reached it, you may want to check your water heater and make sure that it is working.
Cold
No. Both can freeze.
The two pipes going into the heater should be marked with either Hot and Cold or a H and C. There should be a shut off valve on the cold side, but sometimes there is one on both sides. If the piping is visible, you can follow one or the other to where it comes into the house. The water heater is usually the first thing the water line runs to.
no
I always turn on both cold and hot cold water so that the water is warm.
the hot and cold water become together then they make an equal tempature. warm :)