Are there any changes in how spells/ritual magic/alchemy fit into the skill system?
. Not really. All those things are just skills. Difficulties might change some, as may some defaults, but not in any fundamental, earth-shattering way. The one change that will matter is this: “Prerequisite” now means you have 1 point in a skill, not a magic level like “12.” So although wizards are paying 4 points/level for spells, they can just drop 1 point in any spell to get it as a prerequisite. This makes IQ 10 wizards plausible.