error messages

I have found some errors in my pgsql error file:
FATAL 1: Database :"template0" is not currently accepting connections
ERROR: Relation 'visits'does not have attribute 'path'
ERROR: Bad boolean external representation '<font color=red><b>YES></b></font>'
ERROR: Relation "mustdie" does not exist
NOTICE: Adding missing FROM-caluse entry for table "customer"
ERROR: No such atribute or function 'pcustomer_id'

I would like to understand what these statements mean so I can trace and
correct problems in the database.

I do not understand what is the use of the "template0" - is it the base
"model" for newly created databases? I was under the impression that that
was template1...
sorry for my ignorance, but I have to start somewhere... :-)
Philip Jourdan