The 12V winches are also designed to be out in the weather and can be used in wet conditions. Haven't seen 110V winch designed for those conditions. I wouldn't want to use a 110V winch in the pouring rain while standing in a mud puddle.
Minimum rating is 1-1/2 times the weight of the vehicle but this rating is for when you are getting axle deep stuck in mud. If you only need to get out when you lose traction, you can get by with less. This is my use and already had it sitting on the shelf from my jeeping days so I mounted a 9,000# warn to the front of my truck despite it's loaded weight of 10,000#. Figured better than nothing and with the block, should get me out of most places I'm willing to take my rig.