Master edition, maybe I missed something?
Please don’t laugh at me. 
Ok, so magic. How are the spells determined? Quantity and type?
Are they rolled or do players get to choose any and they occupy one inventory slot?
Top of p47 & 49 - INT spells take up inventory. WIS spells dont.
You allocate an amount at character creation usually specified in the Character Type as Starting Loot.
P29 gives you freedom to choose up to 5 spells to start with.
Once you’re in game, spells are treated as Loot or Milestone Rewards