I personally wouldn't use any products on her, I would wait and see if they grow out.
The licking could be caused by a couple reasons. One is boredom, the other is allergies. If it's allergies, this time of year the most likely culprit would be a food alergy (most common food alergens in dogs are Beef and Corn). Find out what the former owner was feeding, then eliminate the ingredients in that food. Initially you can try another brand of dog food with a different source of protien (ie lamb instead of chicken, chicken instead of beef), and if the previous food had corn, eliminate that as well. If that doesn't work you either have a differnt food alergy or a behavior issue.
IF she stops licking, the staining should go away soon enough. You can comb/brush the hair in that area regularly (weekly or more often) to assist faster hair growth.
Oh ... almost forgot. There is a third cause that we discovered recently. Some foods, especially the semi-soft foods, and treats, have colorant in them, most often the colorant is red. This red WILL come out in the dogs coat and ummmmm ... waste. Is her waste orangey? If so, colorant might be the culprit.
Sue