Basically, can they be used on-the-fly or are they prep-heavy? They seem very intriguing.

I haven't given that section a proper read-through, but on first glance it seems to be more prep-heavy. Æmbercraft checks are made to create Æffects for armor, weapons, or utility purposes. Using the newly crafted Æffect requires an appropriate skill check. I'm not clear on how spell-like Æffects work, but from what I can tell so far it seems like the same process, except you craft a spell that you use later instead of a weapon or piece of armor. Somebody who's had more time to read through might be able to correct me.