OID Perfomance - Object-Relational databases

Folks,

Because it's a very elegant solution to my database structure issues,
I'm using OID's extensively as referents and foriegn keys. However, I
wanted to see if others had previous experience in this (answer as many
as you like):

1. Is there a performance loss on searches and joins when I use the OID
as a liniking field as opposed to a SERIAL column?

2. Can I define my own index on the OIDs of a table?

3. What is the difference between these two DDL statements in terms of
data access and PG-SQL performance (assuming that table clients has
already been defined):

CREATE TABLE client_addresses AS (
client_OID OID REFERENCES clients,
address1 VARCHAR (30),
address2 VARCHAR (30),
address3 VARCHAR (30)
)
and:
CREATE TABLE client_addresses AS (
client clients,
address1 VARCHAR (30),
address2 VARCHAR (30),
address3 VARCHAR (30)
)

(This is Michael's questions rephrased)

4. Int4 seems kinda small to me for a value that needs to enumerate
every single database object. Within a couple of years of heavy use, a
customer-transaction database could easily exceed 2 billion objects
created (and destroyed). Are there plans to expand this to Int8?

-Josh Berkus

P.S. My aplolgies if I've already posted these questions; I never
received them back from the list mailer.

--
______AGLIO DATABASE SOLUTIONS___________________________
Josh Berkus
Complete information technology josh(at)agliodbs(dot)com
and data management solutions (415) 436-9166
for law firms, small businesses fax 436-0137
and non-profit organizations. pager 338-4078
San Francisco