Yes, the hit rate will be artificially low if you just start the database. Like you say, every block will have to be read from disk initially. The queries you had them run look viable.

Should all the tables be cached? Hey, if you have the RAM, that would be great. However, it's usually not very practical.

Yes, Oracle 8.1.x has a feature that will allow you to setup "keep" and "recycle" buffer pools. See ( [url]http://technet.oracle.com/docs/products/oracle8i/doc_library/817_doc/server.817/a76965/c06memor.htm#11257[/url] ) for explanation of what each does.