On Magicka
Links are underlined in this section.
Schools of Magicka (Destruction, Illusion...)
Canon
What we know as the basics of magicka through all the Elder Scrolls games is, by far, not yet standard - in fact, the Shad Astula academy is only beginning to canonise it as we RP.
Whether or not your character hops along with those nonsensical new trend is up to them, but to a true Master of magicka Wizard of House Telvanni, this is obviously spoon-feeding a complex topic to the mentally destitute.
Clinging to the Schools of Magicka will not make your character look competent, rather the opposite.
Limitations
Headcanon, roleplaying stimulus
If you read deep enough into the lore of The Elder Scrolls, you will find that magicka can do literally everything in the right (or wrong) hands. However, none of our characters is that powerful.
Far more interesting than what a character can do is what they cannot do and how they deal with it.
Perception
Headcanon, roleplaying stimulus, rule mechanism
If your character is a spellslinger, he or she will have a way to perceive magicka, else they could not interact with it. How exactly that works is entirely up to you, althogh you might want to come up with something, even if it's just for the sake of talking to other wizards.
Spellcasting
Headcanon, roleplaying stimulus, rule mechanism
How does spellcasting actually work for our setting, what happens? This is an attempt to create a basic foundation to make sure our characters don't completely contradict each other when they are talking about what they are doing all day.
Enchants and artifacts
Mostly headcanon, roleplaying stimulus, rule mechanism - WIP
A spell or effect can be turned permanent by the way of enchantment. Artifacts can, of course, be destroyed, but in almost all cases the power inside will be lost.
Countermagick
Canon-ish, roleplaying stimulus, rule mechanism
Although the Dragonborn made it look trivial, in our setting it's not as easy...
Portals / Teleportation
Canon: it's complicated
The Beacon
Headcanon
What do you tell baby wizards to stop them from channeling the power of Red Mountain in a hissy fit? That would be the Beacon. When you draw in more magicka than you can control, it will burn you out, leave you empty - if you are lucky. If not, you'll burn like a match, the unleashed power breaking free through your body... Only bite as much as you can swallow. Only channel as much as you can manage.
Of course this might be a myth. Unless it's not? There have been records of numerous Beacons during the Soulburst, after all...