How to configure PostgreSQl for low-profile users

Dear Sirs,

I would like to rent a my application to a number of customer, each with a
dedicated database (and perhaps a dedicated username).

The database will be installed on 'public IP' machine and will be accessed
by internet on standard port 5432 and using ODBC driver from several clients
(whith the client part of the procedure installed on each machine).

My questions are:

It is possible to configure the security policy so that the simple users
(the customer, in this case) can only read, write, update end delete data to
the dedicated database AND NOTHING ELSE, particularly:

- I would like to create each database with a different (customer) username
(only one per database, in addition to the standard user postgres)
- The user (customer):
---- cannot change his own username and the password
---- cannot backup the database
---- cannot read (the text of) the stored procedures, but execute only
---- cannot know the 'existence' of the other databases

Thank you in advance for your appreciated reply.

Domenico Formenton