The first question : I understand it this way :
Why 'anaconda' was made the the way it is.
1) May be ask the developers.
2) Spend a day with Google and the internet
and find some answers.
For a live cd / DVD : I guess that stage2.img,
a "cramfs", takes care of package install, and
with no packages on the live cd, the installer
is different. Thus no stage2.img.
A Fedora live cd is an image, squashfs.img, e.g.
698 MB, which is just a "copy" of a previously