I can jump in here. “eyeballing” I guess describes how I create encounters, having learned on 1st edition. Usually, it works well, but just occasionally it goes wrong. For example, last session we came close to a TPK on what should have been a straightforward encounter when a CR2 Living Doll...
The ToA reference is an aside "Although he is powerful enough to pursue godhood as other liches have done (Vecna being a prime example) Acererak has no interest in being a god..."
I wouldn't qualify that as an appearance!
Obelisks yes. They have been dropped into adventures as Easter eggs since the start of 5e. However, Vecna has not been mentioned in connection with them until relatively recently. I suspect when Chris Perkins first started dropping them in he had no idea what they were for, basically, they were...
What they are called in game is a matter for the DM, but if you consider a monastery as an institution were a group of people gather together to dedicate themselves to serving a deity, then that is effectively what they are, yes.
So a monastery of a war god might be a military academy, a...
I would say that the main difference between the Wasteland and Fallout games is that in the Wasteland Games you create a party (don't know about Wasteland 1) whereas in the Fallout games it's a single main character (+companions).
Other differences: Fallout protagonist is often (but not always)...
They can't afford to care, since everyone's home game is going to be different in any case. Hypothetically, players could have killed Mordenkainen in Curse of Strahd for example.
That’s exactly why he isn’t being used for this adventure. It’s an over-the-top tropy romp that calls for an over-the-top tropy villain from the earliest days of D&D. Not a rounded complex character.