You can but I'd say put a cooler off and if it's sunny have them stand in the sun for alittle but I normally don't give a bath unless it's 70 or above
i would think so but i would suggest to but a cooler on until there dry
It definitely fine if you have hot water and put a cooler on afterwards, but if you don't have hot water, I don't think it would be fair to the horse. Imagine if you had to take a bath in freezing cold water while it was chilly; I don't think you'd like it very much.
If you get them really dry after and maybe put on a cooler
As long as your horse is dry enough and won't get to cold from being wet it is up to you if you want to or not