Your 2nd part about hot, is why blizzard removed /castrandom. So no, i don't think thats proper. You are not deciding to cast that spell, your allowing the program decide to cast a hot. I can tell you everyspell that will come up (theory wise) in a /click sequence. There is no automated judgement of whats going to cast. I think I would stray from this option.

As for the two keypresses, sounds strange but thats still one action one(two) keypress. I dont really see how different that would be from some of our click macros.. why you would want to really do this I have no idea.

If your meaning like
- F1 (press 1) - Toon1 heals Main tank,
- F1 (press 2) - Toon 2 Heals main tank,
-F1 (press 3) - Toon 3 Heals Main tank?

I really dont see how this would be different from

/castsequence [target=maintank] heal,,,
/castsequence [target=maintank],heal,,,
/castsequence [target=maintank],,heal,