I didn't see De Vries being replaced so soon, but you've been living under a Ric if you didn't hear about the short leash Marko was giving him. His clock started ticking ages ago and he hasn't shown anything since then.

I'm pretty sure crossing the threshold = the resolution. So "follow all issues to the door" means paying attention when the issue is resolved. Things generally don't get as much attention during the follow-up as they do during the initial shock of it.