Currently, I can only deploy three but some of the ships have bigger drone bays and I can't deploy them all. How do I increase the number I can deploy at one time? Is it skill based or something else (additional)?
TL;DR Until you get to capital ships (IE, carriers and motherships) there is no way you'll be able to control more than five drones at once. That said, with the right rigging and training, five tech2 heavy drones can do truly ridiculous amounts of damage. Ask your local Gallente ship dealer for a demonstration of the Ishtar.