#1 Edit the accounts within Outlook and tell them to not check for mail automatically. When you want to check for mail press the F9 key on the keyboard when you are in Outlook. This will tell Outlook to check for new email.
#2 Yes, edit the accounts again and tell Outlook to leave the message on the server. This will leave the email on the server, however you will need to delete the messages at some point otherwise your mailbox will fill up.