10.9.7 Gnus in a dial-up environment

• [7.1]: I don't have a permanent connection to the net, how can I minimize the time I've got to be connected?
• [7.2]: So what was this thing about the Agent?
• [7.3]: I want to store article bodies on disk, too. How to do it?
• [7.4]: How to tell Gnus not to try to send mails / postings while I'm offline?