For item 3, the way I do it is open each discussion that I want to view in a new tab so that the content page doesn't change. After I am done reading/commenting on a particular discussion I just close the tab and go back to the content tab (although I actually use inbox instead of content page).
Mark for your 1st question, set a bookmark for the content page.
For 2nd one, no option yet. I've raised a request already.
For 3rd I prefer opening into new tab like Jamil said.