Thanks for your message. Let me try to give you some quick answers:
Your question: “E.g. if we install Themes, Microblogging, Mobile, News and Menu editor: do we need the Linchpin Manager? Will there be features that do not work if manager is not installed?”
My answer: All features will work. But if you want to have personalized news on the dashboard or in the app, this is only possible with the Linchpin Manager. Otherwise it’s a “one for all” approach. For a consistent layout between theme and menu the Linchpin Manager is necessary.
Your question: Another question: when we use the Linchpin theme on a space we get a footer like (screenshot) Is there a way to edit that footer?
My answer: Yes, the footer can be edited with the Linchpin Theme Plugin. See here:
Does that help?