Multipano is a function that allows scenery positions to be switched during simulation by either clicking on an "eye" icon or using the up/down key. Multipano sceneries allow you to switch between 2 or 3 different positions. This is a video using multipano by rdeutsch http://www.youtube.com/watch?v=Zk1m-Rv_u7w

Full HD (High Definition) means the addons are compatible with screens that support Full HD or above (1920x1200 resolution)

Also just to add to your questions, the True Sound technology was created by recording the real sound of rc models at various frequencies and then sampling these sounds only to get the best possible realism.

These technologies have added new dimensions of realism to AFPD and they're pretty amazing. However, do take note that you will need to meet the recommended system and graphics card requirements here http://www.aerofly.com/requirements.html