I don't have a complete answer for you; technical questions about the interface like this are better investigated on Meta.SE. Here are a few things though:
If someone has quit/been expelled, all their votes zeroed out, it would seem to follow that their questions were also removed.
Generally no. This is only done with spam or obscentity posters who have contributed no valid content. Otherwise, you can tell content by deleted users because they have a sort of grayed out chess pawn for an icon (although there might be other reasons for that).
Note that deleted content is actually visible to users with >10K rep, and moderators.1 There is a separate category, destroyed (for aforementioned spam etc.), in which case the posts are gone from the system as far as I am aware.
However, I don't know whether the points loss associated with a deleted user occurs because of one who is actually destroyed, or if it is so for any routinely deleted user. The only ones I've ever deleted or destroyed are spam/obscenity cases which have been identified quickly and don't have any further impact.
The longer term more normative users that are axed here were actually axed on the SE network as a whole. This has to be done by an SE employee (such as a community manager, CM). I don't know whether you can delete your own, but I am 99% sure it would not be in such a way that it negatively affects the community. People who go on tantrum sprees down- or un- voting or deleting their own posts would have their behaviour caught by the system and reversed by a CM (and you can't delete your own question if there are upvoted answers anyway).
As far as sorting out the whos and whats, the best tool available, if you know a bit of SQL, is the Data Explorer (see here for more about that). If you don't know SQL, find a tutorial until you understand "inner join" then plug away ;D
The DB dumps used in the explorer are done weekly (i.e., that's not the live database). Unfortunately, a quick check:
select * from Posts where DeletionDate is not null;
Which returns 0 rows, implies information about deletions is missing from that DB dump.2 I'd guess the reason for that is to simplify queries, which mostly would want to exclude them. But again, the folks on Meta proper should have the real truth.
To prevent confusion: A deleted user's content is not necessarily deleted, and deleted content is not necessarily by a deleted user.
In fact I'm wrong about there being no info on deletions in the explorer DB, just noticed the