I was a lapsed gamer, coming from 5e straight from 2e, though I did buy and read 3.5e. Wizards I get, and sorcerers as well. Warlocks are overall new to me, never playing in or running a game with one. While they are present on Eska, they will probably be the least fleshed-out of the options.
Wizards, sorcerers and warlocks have long established histories on Eska. Wizards learn their magic either through academies or through a lone master teaching his apprentice. Warlocks gain their power through pacts with powerful entities, while sorcerers come by their magic naturally. I see them more like mutants or super heroes, whose powers manifest as spell like abilities.
The elves, especially the mith'edhel have always sought to control wizardly magic. The grey elves run the traditional magical academies. In their usual haughty and arrogant views, the other races are not worthy of admission to their schools. The occasional exceptional applicant does gain admittance, however.
The mori'edhel have a long tradition of shadow magic as well.
The rock gnomes have perfected the school of animation. Wizards of this school were the driving force behind the creation of the warforged.
My sorcerer house rules have now been bundled into Grognard's Grimoire: Sorcerers, available on the DM's Guild!