Psychic Vampire and Magic Abilities
Are the following abilities affected by Psychic Vampire:
Counter Magic, Medicate and Summon Vortex
Yes, anything that is on a model's card under the "Magic ability" section is considered a spell. By using that ability, the model is considered as casting a spell and would suffere damage from Phychic Vampire.
Infernal for Hire
When a model casts a spell while in the area of Psychic Vampire, it takes a point of damage. Any ability listed under Magic Ability is a spell (Prime page 83). As long as those abilities are listed under Magic Ability or on a warlokc/warcaster's spell card then they are spells.
If you are referring to the Druids of Orboros, they have all three under Magic Ability, so those would be considred spells.