The aluminum will dull the carbide. If you go slow, it will cut it for a while. If you have a lot of cuts, I’d expect to throw the bit away after you’re finished
yes. I did it in old barn siding.
Not sure about the sales; but, Diablo is made by Freud. The bits are of very good quality, exactly the same as Freud (except for color); but, according to an article I read, Freud is less expensive in some cases.