Beginners in Oracle; Need some advice!

We have recently purchased an Oracle System and are in the process of setting it up, however, there are some things that I am not fully clear on.

1. How many Instances (SID's I assume) can I run? We have one HP9000 server (UNIX 9.04): I would think only 1!
2. Is an instance the same as a database?
3. What are segments then?
4. If we have a production DB and would like to do development and testing, then I assume that separate DB's would have to be created: 1=production, 2=testing (?) Is this right? OR am I supposed to create a segment for the tables that are to be tested on and then drop that segment when the applications are in production???
5. I am a little puzzled about extents too. How do MAX and NEXT extents work? Am I correct in thinking that I have to "export" the database every month or so to tape to "defragment" the DB?
6. What are the different users and how are they different from the users I create? Is there groups of users that can be created like DBA's, USERS, DEVELOPERS, then under these the individual people?

	SYSTEM
	SYS
	SYSOPER
	SYSDBA
	Joe
	Mike

	What is the "oper" group that I created on UNIX for?

    When we create applications, does it have to be distributed to each user's "directory" or it 
    can just be put on the server and those that have permissions to it (through groups or      

        Does each user get assigned to a particular rollback or redo log to reduce congestion?

7. If I have around 40 tables, how may I distribute these?

	CUSTOMER_SERVICE segment	8 tables
	INDEX segment			6   "
	QUALITY CONTROL segment		5   '
	TESTING segment			any tables that are being used for development
	INVENTORY AND SUPPLY segment
	TEMP segment
	etc.....  [Does this logic make sense?]


	   OR

	Put all 40 tables in 1 place?
	

Any Help would be appreciated! I think getting used to the terminology is the hardest part.

Thank You!

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