Hello, everyone! :)
It's so good to hear that there is interest for this. Due to such interest, I will be posting up an OOC sometime nearer to (or during) the weekend, since in the middle of the week, I am focusing on my work and classes right now.
Regardless, before the OOC, I'll address the current concerns.
"Are you going to be looking for Players to be signing up for Coven positions, or more of a foot soldier-esque kind of role?"
- In short, yes and yes. Now, let me explain: as stated in the little, bullet-pointed overview, within the first post, coven are much more structured and political in this realm. Attribute them more closely to a medieval, noble household/group of people (such as a duchy or some other thing); the people within may not be related and may have different roles, but they align under one name. In other words, all players will have their characters be in the coven (meaning a part of being a resident in the castle/household) but their actual role may be something else (such as a foot soldier or whatever else). In the OOC, I will add a little section of ideas and suggestions to the roles within the castle and coven, in light of this question.
As a side note: witch is a broad term for any person who is a part of a coven (which has been defined above). It's a state of affiliation more than a quantifiable position. You can be a witch and a servant, or a witch and a count, for instance.
"Also, are you going to keep the Magic possibilities to a more narrow approach(Kind of like "Healing/Offensive/Defensive" varieties), or are you going to let the Players -kind of flesh out the options with a broad generalization with what would be acceptable without stepping out of bounds (More of like Elemental/Necromancy/Curses/etc)?"
- Within the IC, magic is being approached from a very ambiguous and natural way. It isn't a science in the slightest; it's not studied at all. Rather, it's very intuitive, so these classifications of "healing/offensive/defensive" and "elemental/necromancy/curses" are both too specific; they add too many constraints. That isn't to say there isn't a basic organizational system formulated by the people, within the IC, such as calling one set of spells 'charms' and the other 'curses'; but this is to say that magic and spells can work in a very broad, general way and a specific one. There may be instances where someone will do something akin to telekinesis, like that of a superpower and not pure magic, as well as instances of a traditional, elemental fireball.
The reason behind this madness is based on the premise that magic is very integral and present in most aspects of the realm. Although spells may be devastating, awe-inspiring and noticeable, magic in general is very common and regular, not given all that much attention by certain people. A very rough comparison would be to breathing in our world. Truthfully, it is one of the MOST important things we can do, allowing us to live, but because everyone does it, it isn't exactly spectacular. Still, there are situations when breathing is really noted and revered in our world (after holding your breath underwater for a long time, or when belting out a long note). In a similar way, this is how magic is.
Another rough illustration would be found in the Harry Potter universe (within the Wizard world specifically). Since everyone in the wizard world uses magic, there isn't much of a system to differentiating magic users (I mean there are basic ones and also very rare, specific ones [like an animage] but in general, there isn't). Voldemort isn't a necromancer, and he doesn't confine himself to only necromancy. To continue the example, the difference between a curse, a jinx and a hex can be pretty gray at times, and in essence they are the same thing; the only difference is to the damage it causes which can be an obscure thing to quantify.
To conclude though, in the OOC, I will be providing a reference in the actual formulation/RPing of magic and spells. It'll still be freeform for the most part, but it will have necessary constraints in order to achieve a cohesive and consistent magic system. This will be explained in the OOC.
"Will our characters have to be magic users?"
- First, see the answer above; using this answer, I can safely say that, in pure technicalities, EVERYONE will be a magic user, but it is on the use and volume of the magic that characters will differ. A witch devoted to battle with a sword (with perhaps magical augmentation) may use magically differently and maybe to a lesser extent, in comparison to one who avidly uses magic as a constant form of divination, consulting the occult for answers and guidance to everything.
I hope this has cleared some things up. Remember, if you have any questions whatsoever, to ask them. :) I will do my best to respond; these questions do not only help you; but, others, me and the RP in general as well.