DB novice questions

Hello Gurus,
I'm new to Postgress world and before start creating my first database
for test.
I have some questions, beware  I have  experience with other RDBMS.

1- when  issue create db , is there a option to specify the database
page size ? what's the default ? ( don't see any comments in docs)
2-any basic tips for cfg to achieve some reliable  database I/O
performance , my  first toughts are to create at least 2 additional
table spaces: one for indexes and one for data.
when creating the db , how can I specify a separate table space for :s
ystem catalog , data and indexes ?( any special syntax , can't find to
many examples in PG docs)
3- what is   the best practice to use ad owner for a db , if I create
the db as user: postgress   , any implication for not using this  user
as owner of all db's ?
 thank you
Isabella