Yo, thanks for making the thread. Okay, so your characters sound good. I'm going to have a male mage, and I'm thinking a sellsword as well. Really rag-tag group; also the pairing of a mage and witch will serve to highlight the magic caste system.

Speaking of which: magic is all based on the user; people are born with an innate level of magical energy (from none to nearly superhuman, in a typical bell curve distribution). This reservoir is drained by casting spells and refilled over time by rest. Types of magic include elemental (fire, water, air, earth), healing/modification (heal wounds, repair damage, cure diseases, alter appearances), environmental (levitation, teleportation), creation/destruction (usually in conjunction with elemental magic), intrapersonal (mind reading, mind control, magic-enhanced interrogation or persuasion), necromancy (reanimation of dead bodies), attack/defense (creation of magic shield or weapons), plus miscellaneous others. No spells are inherent, but must be learned, however, many spellcasters are self-taught. Although common, magic is treated as any other tool or weapon: if you use it wisely, most people will have no problem. If you abuse it, expect the pitchforks to come out.

Magic is practiced by multiple discrete groups: Mages, Witches/Wizards/Wixes, Warlocks, and Petty Magicians. Your average person falls into the petty magician caste; usually they can do one or two minor spells (light a small fire, heal a minor wound, levitate a rock) but not for long durations or multiple times. Wixes are usually mid to high-mid levels who are self-taught and organize in very small groups if at all, and use magic as part of their living (either doing magic work for those with less ability or using their magic to aid in a non-magical job). Warlocks are almost universally individuals practicing magic for their own purposes, usually nefarious, and frequently dabble in 'banned' (or generally unaccepted) types of magic like mind control and necromancy, and tend to be high-mid to high level. Mages are groups of high-mid and high level spellcasters that are usually well-organized and frequently work together to study magic, train and hone their spellcasting, and generally sell their services to agents of power (anything from kings and queens to mayors).

Any individual of any level can be in any caste, however, generally speaking one's innate level of magical ability determines which caste one can potentially join - those with low levels of magic rarely become mages, those with high levels rarely live a life making minimal use of their magic. There is no easy way to determine one's potential except trying it - every possible form of magic is open to anyone with even a drop of magical ability, but the level determines how much/to what degree they can cast a spell. As well, mid-and-above level spellcasters tend to practice a range of magics, but not all do; specialists are not uncommon either.

Now.. any further questions or is the magical context about set (and are there any glaring inconsistencies I've somehow overlooked)?