File Types Page

Forgive me if this has been explained somewhere, but I can't seem to find the details I am looking for.
I am streaming a combination of MP3, M4A (some lossless, some lossy), AIFF and FLAC files to a Squeezebox Radio, Boom and Duet.
No other file formats are present in my library.
Bitrate Limiting is set to Disable and LAME Quality Level is set to 0 (Highest Quality, very slow) for each of my players. I have no issues with stuttering and/or choppy playback.

On the File Types page, I'm not quite sure how to interpret the available options.
For instance, starting at the top, you have:

File Format-----------------Stream Format

AAC------------------------AAC [Native or Disabled]
----------------------------FLAC [faad/flac or Disabled]
----------------------------MP3 [faad/lame or Disabled]
----------------------------PCM [faad or Disabled]

1- Why do I have options to stream AAC using these other formats?

2- What determines which Stream Format would be used?

3- Wouldn't you want everything to stream native? I understand transcoding to a lossy format if bandwidth is a concern, but why give the option to transcode to another format that is likely to be the same work for the LMS CPU?

4- If I want everything to stream native, should I just choose "Disable" for the other Stream Format options given for each file type that has native streaming support?

5- Is there any benefit to disabling all the other file types that do not apply?

Any info would be greatly appreciated, as this has been in the back of my mind for quite some time.

Thanks!