2) A doom token is added any time a new gate is opened. But if the gate doesn't open (for the two examples you gave or if the scientist is there), the doom token isn't added. A doom token is also added if the terror track is already at 10 and a new monster surge overloads the outskirts limit. I'm not sure but I think failure at some of the rumors might also add a doom token.
If the Terror track is at 10, why are monsters still being added to the outskirts? All new monsters should go to the game board since the monster limit in arkham isn't in effect anymore..
It is however true that if the terror track should rise above 10 for any reason due to some card or other effect, a doom token should be added.