AS to source material:
As of 2009, the most common acquisition medium for digitally projected
features is 35 mm film scanned and processed at 2K (2048×1080) or 4K
(4096×2160) via digital intermediate. Most digital features to date
have been shot at 1920×1080 HD resolution using cameras such as the
Sony CineAlta, Panavision Genesis, or Thomson Viper. Cameras such as
the Arri Alexa can capture 2K resolution images, the Red Digital
Cinema Camera Company's Red One and Red Scarlet can record 4K, the Red
Epic 5K, and Sony's F65 CineAlta camera can record 4K down-sampled
from 8K. The marketshare of 2K projection in digital cinemas is over
98%. Development of the 4K Dalsa Origin was terminated by Dalsa
Corporation in 2008.
So recording in 16:9 is not gonna be a problem.
When all of the sound, picture, and data elements of a production have
been completed, they may be assembled into a Digital Cinema
Distribution Master (DCDM) which contains all of the digital material
needed for projection. The images and sound are then compressed,
encrypted, and packaged to form the Digital Cinema Package (DCP).
For technical details, see this link for an overview: