what is and who owns postgresql type of questions

Hello.

I've been using postgresql for two years now, and someone recently asked
me some questions about it which stumped me.  Could anyone on the list
point me to the answers to these questions:

1) PostgreSQL is copyright the "PostgreSQL Global Development Group."
What is the "PostgreSQL Global Development Group"?  Is it a non-profit,
a company, or some other kind of entity?

2) Does the "PostgreSQL Global Development Group" own the source code of
PostgreSQL and release it under the BSD license?

3) Does it also own the "PostgreSQL" trademark?  Or is "PostgreSQL"
trademarked?

4) I noticed there is also a PostgreSQL, Inc. in Canada, and they
provide the servers and facilities for the postgresql project.  Other
than that, are they just another consulting/support organization for
PostgreSQL, or are they also the main organizers/sponsors of the project?

Thanks,

Si Chen