Can you tell me what is the total amount of ext,Ican have on primary cover for the operator thank you

You can have a maximum of 30 coverage groups , each with an unlimited number or members. (Primary is immediate) and (Secondary is delayed) coverage
Hope this helps
dtmf

You are allowed a maximum of 8 exts cover another ext. Another way to set this up is by using shared system access programming. That will allow another 8 exts

I have had this problem myself. I read you can have ten, but I have only been able to administer 8.

Only an operator setup as a DLC will allow other phones to have coverage of it. If you have a QCC there's no way to setup coverage on other sets.
Also - the limit is 8, regardles if they're primary or secondary