Can I merge redundant buttons through macros?

I used macros to minimize button clutter in WoW but not sure if I could do the same here.

Examples:

• 1-button to cast 4 different spells by using modifier keys (shift, ctrl, alt, or no mod).

• 1-button pet summon: If Emerald is out, pressing it again would summon Topaz, and vice versa.

• 1-button Shining Topaz/Shining Emerald, or 1-button Backdraft/Downburst, depending on which pet is out.

Is this possible?

First: Those would all be 4 different keybinds.
Second: No
Third: Macros can do this. Example:

/pac "Shining Topaz" <t>
/pac "Shining Emerald" <t>

The other line will not do anything with the wrong pet out so no harm.

Thanks a lot for the clear answer!