I will attempt to answer one of your questions, but I do have a couple of questions for you.
When you are trying to set permissions for your cgi program, how are you accessing the cgi-bin folder? are you using a ftp program, or putty? How are you loged in, as a user, or as admin?
Check out
http://wiredgorilla.com/main/article67.htmlRemember that linux is case sensitive.
Try issueing chmod 755 tester.cgi (unless the "t" in tester is a cap)
The email problem is kind of explained to you in the error message. Your server appears to the rest of the world to be an email relay. These are stopped by many mail servers because it is one way spammers send their trash. I beleive it is because your ip is showing up as belonging to some one else (SBC). If your terms of service allow you to set up a public server, I think your problem may be resolved by requesting a reverse dns entry by your isp.
I know there is someone out there with a better handle on this. I ran into the same problem when I first set up my server, and I think the reverse dns took care of it