No, you generally do not capitalize case manager when used in a sentence. The only times it should be capitalized are at the beginning at the sentence or as a title on something like a business card.
"Project manager" should be capitalized when it is used as a job title or precedes a name, for example, "Project Manager Smith." It should not be capitalized when used generically, such as "the project manager."
Ofcourse line manager
Only if it directly precedes the name of the manager.
A noun is capitalized when it is the name of a person or place. Therefore, when you are addressing a manager by their title, you would capitalize: "Yes, Manager". When you are referring to a manager, and not using as a replacement for their name, you would not capitalize.
Yes, the word "manager" should be capitalized when it is used as part of someone's job title or as a formal title for someone in a managerial role.
Yes.
Only if it directly precedes the name of the manager in question.
Yes, you should capitalize "About" in a title.
Yes, "North" should be capitalized when referring to the geographic region that is north of the Mason-Dixon Line. This helps differentiate it as a specific region.
Yes, you should capitalize the C in Century.
No, you should not. You should only capitalize a word when it is at the start of a sentence or when it is a proper noun.