Are you sure that the fields in question are linked to the AD
information? You can check this by going to Shared Services
Administration > User Profiles and Properties > View Profile
Properties at the very bottom.

It's got all of the stuff mapped, so I'm finding it a little odd that
it's not getting those updates as they happen. (I've been manually
starting a crawl after making AD changes.)

All profile  imports from Active Directory to the Profile store are
scheduled. Many of the properties for the user  object are not
considered priority. So, many property updates are not copied until
a property with priority status is copied over to the Profile store.

Ok, interesting, that does explain part or all of what I'm seeing.

So let me throw this out: I've noticed that my full import  and
incremental import are both "custom." I've no idea why. I'd like to
change that so it's from Active Directory. Will this cause me problems?
(Will user  accounts disappear, or anything strange like that?)

There is no two way synchronization between Active Directory and the
Profile Store. There is only a one way copy, tagged as
synchronization, from Active Directory to MOSS's profile  store.

You can leverage the Identity Integration Server 2003/2007 to
configure that two way synchronization. Also, there are some 3rd
party products.

If you go into the custom profile  import, what type of
settings does it show? Our profile import  is set as
custom because we pull our profiles from our global
catalog servers. Because of this, it needs an
alternate port to be used.

Yeah, I'm pulling from a GAC server too... Does MOSS configure the import  as
custom automatically if you are pulling from a DC that's a gobal catalog too?
(Would that explain why it's custom?)

My big question is: If I change the settings to AD, as opposed to custom, will
it simply update the users I've imported into MOSS? (As opposed to doing
something wacky, like zap them...)

I think MOSS pulls from the ot DC OOTB based on the server's Domain. If you
modify the Search Base e.g.,(DC=MyDomain,DC=org) or the user  Filter
((&(objectCategory=person)(objectClass=user))) then it becomes a Custom
connection.