[quote=@Dumb1And1Lazy]1.) Since I wanted a mage, I took one skill slot for general magic and one skill slot for his specialization. Is that alright or can I only take single schools? Like since I took general magic am I allowed to use the basics of all schools of magic and one specialization meaning I can be amazing in that one school or is it like magic's rare/grounded enough that I'd need to pick a specific school and just have the basic ability to perform that one school?[/quote]

One skill slot for general magic would mean basic ability in all schools of magic, yes, not unlike a jack of all trades. Taking a skill in a certain type of magic would mean that your character would be skilled further in said school than the average caster.

[quote=@Dumb1And1Lazy]2.) I wrote in a magical college into his backstory, do those exist or are wizards in small scattered groups?[/quote]

Mage colleges do exist, yes. They're more prominent in elven cities, but they do exist. Smaller groups/factions such as harvest witches (a minor form of druidism practiced by those that have a small control over nature magic) also exist.

[quote=@Dumb1And1Lazy]3.) How does magic work? Mana or slots? You said it causes exhaustion so I assume it's Mana based and people can just use mana energy to affect the surroundings/themselves. Like Shadowrun[/quote]

Magic, including religious-based magic, functions through mana. Whereas everyone has some sort of magical affinity, it requires years of formal teaching to cast something that actually looks like a spell. Students at mage colleges might learn how to sling fireballs, priests/clerics/paladins-in-training would learn to mold their faith into magical abilities, and so on and so forth. While those with spells under their belt can cast any of them (though more complex spells may require time and reagents/ingredients), too many spells cast without a momentary rest will leave the user drained and weak, unable to cast anything. Of course, this can be ignored through the use of potion/crystal use, but too much of either will eventually create an addiction to the substance.

[quote=@Dumb1And1Lazy]4.) Can I get a measuring stick on what's possible to be done by mages/magic both in a general sense and when they specialize? Like generally what's possible with magic and how much stronger an evoker can use offensive/evocation magic than a generalist/non-evocation specialized mage[/quote]

With magic, almost anything is possible. Life can be restored or just as easily drained away. Rains of fire or blizzards can be called down upon an opponent. Constructs can be forged and weapons can be enchanted through the use of magic. It mostly depends on what the user is skilled in, and how knowledgeable they are in the magical arts. As for how stronger a proficient member of a certain school would be over a generalist, the difference would be noticeable. A generalist might know how to cast a fireball or two, but someone skilled in Fire magic could potentially cast a storm of fire from the sky or even turn a foe into a living bomb.

[quote=@Dumb1And1Lazy]6.) I realize I might have misunderstood magic descriptions. With there being Arcane, Rune, Holy and Nature magic, do schools of magic even exist?[/quote]

Those are the schools of this universe, though I suppose one might consider them "types" rather than "schools". The ones I listed are just some of the possible schools that one can practice. There's Arcane, Fel, Necromancy, Nature, Holy, Shadow, Rune, Blood, Elemental (also broken further into elemental magic like fire), and so on and so forth. No one is certain how many schools there are, especially since some spells combine schools such as Astral magic (which is essentially divine nature magic) or Shadowflame magic (shadow and fire mage combined).

EDIT: Missed #5. No, a knight or a general fighter can not use magic to supplement themselves unless they've trained to do so, like a spellblade, or a paladin.