How to spot vehicles when flying a jet

 A  and  D  are used to to control your yaw (horizontal turning), while ↑   and ↓   control your pitch (vertical turning) and ←   and →   control your roll (rolling counter-clockwise and clockwise, respectively).

To make sharp turns, you need to roll in the direction you want to turn, while pitching upwards and at the same time (if you're not completely vertical, if you are then just keep pitching up) yawing in the same direction.

For example, to turn right, do the following: →   until you're almost vertical, then hold  D  at the same time as ↑   (for regular flight control, for inverted flight control, just hold ↓   instead).

Yes, you can. The same principle applies as when you are on foot, in that you need to be looking in their direction and not have them in your peripheral vision. The same applies to all vehicles.