It depends on what you are going to use the picture for. If it is for personal use, or if it is going to be sold as "Art", then you do not need a model release. If you are going to use the picture for commercial purposes, i.e. to sell a product or service, then yes, you need a model release from every person in the image.
If you are flying the drone for fun or personal use, then you do not need a license. If you are using the drone to make money, by selling photos or video taken with the drone, or using the drone for something like inspections, then yes, you must have an FAA license.