I have someone i know in Unit 29 at Parchman. This someone had advised me they might be in trouble with a particular gang over some property issues. Is this common? Are the corrections officers aware of the structured "systems" and the unwritten prison rules?

Yes they are aware, and there is little to nothing that can be done.

If he doesn't settle - it is life threatening - if he tattles or "snitches" then he will have to reamin on PC (Protective custody) the rest of his stay.

what jonathan says is true.. i know a guy who is in PC for the rest of his stay.. his gf is a friend of mine.. they have gone so far as to make her pay them 2000$ or they were going to kill him.. and she even called the warden of the place he was at, at that time...(not parchman) and he could not do anything about it! she had to pay the money.. well he didnt go to pc then but now that this has happened so much he has had to get help from the prison syestem.... now he is in parchman in pc for the rest of his sentence... and if i am not mistaken (i may be) he dont get contact visits in PC... but i might of mistaken what she said...