ok, personally, I would LOVE to have cat ears, or a fox tail, have a dragon to help me get wherever, be friends with a wherewolf and stuff like that. But it's not real sadly, the only way for that to happen is in the astral plan [the tail, try riding a dragon you don't know and you're in trouble] my point is, i see how it would be fun, why people ask these thing, unfortunatly magic has limitations remember:
magic works in the restrictions of physics/science/reality you cannot use magic to change these things, sad but true.
magic is energy. spells/chants lets us focus our energy and use it to change the odds in our favour. we can use it to heal, for luck, love, beauty, clairvoyance, and to harm [may be forgetting some]
and one final point, a spell/curse is only as strong as you make it out to be.