get your configuration variables correct, or it wont work out-of-the-box (kernel.shmmax, autovacuum, shared_buffers)
The only thing you really need to worry about is making sure the kernel SysV limits are appropriate (kernel.shmmax); autovacuum and shared_buffers are configured reasonably out of the box.
GSQL depends on authentication of the OS ("sameuser" on pg_hba.conf)
That depends on how PostgreSQL is packaged by your OS.
Learn about template databases. Your first database is a template database.
No; the default database is called "postgres", and it is not a template database.
I use ubuntu all the time, I don't remember having to configure shmmax to get it working with my blog. I think you only need to mess with that stuff if you're trying to increase the number of connections or "scale" your blog. I think 90% of the people who use mysql, use it without touching a configuration variable, and those people could just as easily use postgresql without configuring kernel.shmmax.
I don't know, but I'm guessing that 90% includes people messing around with django/rails/lift etc, or they're running a blog/cms/wiki on some shared virtual hosting somewhere.
The only thing you really need to worry about is making sure the kernel SysV limits are appropriate (kernel.shmmax); autovacuum and shared_buffers are configured reasonably out of the box.
GSQL depends on authentication of the OS ("sameuser" on pg_hba.conf)
That depends on how PostgreSQL is packaged by your OS.
Learn about template databases. Your first database is a template database.
No; the default database is called "postgres", and it is not a template database.