2. Yusuf along with everyone else who wakes up after the van drops will be woken up by the flight attendants who are managing the drug being put in everyone systems. Either by a drop on the plane on turning the drug off and they awaken.
3. As seen earlier in the movie there is only one way out of the lowest level limbo and that is by killing yourself. It is difficult because in the limbo level you forget that you are dreaming so killing yourself feels like suicide. Cobb comes to Saito and together they remember who they are and the deal they have made. A gun is seen on the table implying they will shoot themselves in order to wake up from the dream.