Well, I think we first need to understand the theology behind "losing salvation". Judging by the phrasing in your question, I assume that you're coming from a Calvinistic theology. The question is along the lines of thinking something like "we are saved from sins past, present, and future". Continuing from that theological stance, I would say you also have incorporate ideas like pre-destination, irresistible grace, and especially the perseverance of saints to understand "true" salvation (regeneration, transformation, etc.). See THIS website for a good break down of the five points of Calvinism (basically a five point rebuttal of Arminianism, which would argue that we CAN lose salvation). That will help you answer the first part of your question about "losing salvation".

The second part seems much more simple to me. Jesus came to Earth to die for the sins of HUMANS. We (humans) are made in the likeness of God, and have free-will to accept his gift of grace or not. Satan is, obviously, not human and not made in the likeness of God. He is a fallen angel and was around before the creation of humans. I don't think that any angel can have "salvation" in the traditional sense. For one, they live in the presence and knowledge of God so they don't have free-will or faith in the same way that we do. There is no need to believe in something "invisible" since they are in the presence of God. Therefore, Satan did not have a "salvation" to lose, rather he rejected (continually rejects?) God, is a slave to his sinful pride, and is forced to live in hell (eternal separation from God).

Hope that helps!