[Akkorian]

There’s no way for a macro to do what you’re describing. You can’t cast a different spell each time you press the button without using a cast sequence, and you can’t switch targets in the middle of a cast sequence. Macros also can’t tell whether you have a spell on the cursor, or pick a target for the glowing hand. Blizzard wrote the macro system on purpose so that it’s not possible to have a macro (or addon) that makes decisions like that on the fly. Even though what you’re describing is probably something Blizzard would be okay with, there’s just no way for them to make it possible without also making it possible for macros to do lots of other things that Blizzard isn’t okay with.

With the macro I posted before, you can also self-cast by holding down the Alt key while pressing the key binding for the button it’s on. You can change the Alt to Shift or Ctrl if you like, and remove the btn:2 part if you know you’ll never click it.