I'm surprised no one has answered you. Maybe it's because they're jealous of your natural color?
Tons of CG's color their hair at the salon, and at home. I know a stylist will say their hair color is less damaging, but honestly I really think it depends on what you're going for. If you're going for a color that requires lifting hair color, then maybe you are better off going to a stylist. But if you're going for something else, like depositing color, then by far I have had way better results doing it at home myself and have experienced less damage doing it myself than at a salon. I'd say that most people experience damage at home because they may have done it wrong, and needed to go get it fixed at a salon anyway, which will all know is bad news.
I'd say take it to your friend who's a professional to do it the first time - at least if you want to do it yourself eventually, you'd get to see how they did it the first time to get an idea and ask questions about how you could maintain the color yourself at home. I think an auburn with highlights like what you described would look really pretty on you! In general, if the hair color is permanent, it's more damaging, but if you're going darker than your natural, then you could get away with a semi/demi which is usually just depositing color and far less damaging.
Good luck and post pics!