[AccessD] Primary Key Best Practices

I need a few good references (preferably electronic) on the Best
Practices for defining Primary Keys (PK)
Here at the office we have had a few heated discussions about primary
keys.
I don't' mean to stir the pot on this list, just curious what others
think.

1.  All tables should have a primary key even though it will not be used
as a foreign key (FK) in another table.
2.  PKs should always be an autonumber (Access), Identity (SQL) or GUID.
3.  Avoid complex PKs such as two PKs from two other tables.
4.  Avoid complex PKs such as two fields from one table.

You could probably come up with some more.

Thanks,

Jim H.