There is no spell that can take a persons free will away from them or that can cantrol another persons mind. You can implant thoughts, you can take advantage of natural desires and tendencies to push them in a direction but when it comes down to it the final decision is as it has always been theres to make.
depends. love spells that cast on another can work, but they won't work forever, you're overpowering the person's free will with your own. this won't take their will away forever, just temporarily weaken it.
i remember reading about a voodoo spell that turns people into zombies, while many believe it's the work of magic, it's actually poison from a fish [a sea urchin if memory serves] that temporarily paralyze the person, [similar to rohypnol except they can move] and they are forced to do odd tasks but it wears off within 24 hours. keep in mind i read this a few years ago and haven't looked into it further, my point is you can use poisons and plants to alter people, but in the end, it wears off like any other spell like that. also, if you follow the Wiccan Reed, forcing your will onto another goes against it, so you shouldn't cast the spell in the first place.
A spell can not make someone love you, period.
As far as being able to control someone against their free will, yes that is possible, read up on mind control.
Or about slavery, or prisons. But by the use of magick alone, I am not so sure.