Hmm... do you easily get nausea from playing games, car sick and such? I suggest you to use the witcher sense in stationary view and not move around while using it , just look at one direction and activate the witcher sense, release the witcher sense and look at another direction. The witcher sense's reddish trail will remain for a few seconds even after you disengage it.
Yup, Geralt is a warrior class with minor magic sub-skill. The only sorcerer-like character with powerful magic in the game I believe is his lover Yennefer. Since the developer said this is the last Witcher game, hopefully their next RPG will have different classes to choose (such feature is a norm in modern day RPG).