LainieH - This certainly would require a customization, the first one is however a simpler one compared to the 2nd. You would need to add some jQuery to your header to check the links on the page and add the _blank attribute to them. A snippet like this:
$('.lia-message-body-content a').attr("target","_blank")
For the second one, I would say that it could be possible theoretically but you'd need to make some API calls while the user is posting. As soon as the user posts a link, you would need to check for the respective details such as title, description etc. This is similar to what happens in the Jive community.
I hope it helps.
