For the summons, try
Code:
#showtooltip Summon Succubus
/cast [nopet:Succubus] Summon Succubus
I would suggest a single button for the ability, so you can use the same irrespective of which pet is out.
Which would be assuming the use of only a single ability.
Code:
/cast [pet:Voidwalker] Sacrifice
/cast [pet:Succubus] Seduction
/cast [pet:Felhunter] Spell Lock
Change to other abilities if need be.
That could be adapted to use the following which will cast sacrifice if in combat, and Consume Shadows if not.
Code:
/cast [pet:Voidwalker,combat] Sacrifice;[pet:Voidwalker,nocombat] Consume Shadows
There are also options for perhaps two abilities based on a modifer key being held down, say for devour magic or spell lock, but I have given you plenty to work with already, and I am sure there are better ways to do some of what I have done there.