As the title says, my fundamental question is: How well do the older books for Mage the Awakening 1e work with 2e?
This question: Which Mage: The Awakening sourcebooks are essential? is obviously related and Which Mage: The Awakening sourcebook (if any) has info on mages' daily, non-adventuring lives? is tangentially related.
This almost comes down to "How much has changed between the two versions?". If there are fundamental differences, then the older books will be of no help and I'll have to wait for updated versions. If the changes are minor, then likely all of them will play well. It could also be that some material that was formerly supplemental has now been incorporated into the core making a prior book less appealing.
I am particularly looking at "The Tome of Mysteries", but that book also looks like the one most likely to have been superseded either by rules changes or having its best material built into the new core book.