Complete documentation for DNW

I was give the link to the Friendly arm downloader instructions for DNW,
but I don't understand what a lot of options are, such as on page 5 of that
document (download from http://www.friendlyarm.net/dl.php?file=download.pdf
)

Please provide documentation or explain what all of those options mean in
more detail. 

For example, what does "download zimage into ram" mean? What is a zimage?
And what is vivi?
And what is a root_yaffs image?

Yes, I'm new at this, and yes I could likely search this, but I have done
lots and lots and LOTS of research, and it's frustrating and very time
consuming that sooooo much info is scattered every-which-where making
Understanding this stuff really hard. And sometimes I do find the info I
need, but I don't know it because it isn't clearly explained what the info
is for... I'm getting there, but it's soooo slow, I'm very busy with many
projects, and I'm in a time crunch on this one!

Thanks!

Since there are no responses, here's some info I had to, yet again,
research because no good documentation exists in a common location:

A zimage is a compressed bootable linux image, see
http://en.wikipedia.org/wiki/Zimage

vivi is a bootloader. See http://en.wikipedia.org/wiki/Booting#Boot_loader
for more info on bootloaders

YAFFS is a file system designed for NAND flash. root_yaffs likely has
something to do with yaffs being used for the root filesystem. See
http://www.yaffs.net/yaffs-internals

NEW QUESTION THAT I HAVEN'T FOUND AN ANSWER TO YET:
I see many comments of people who want to replace vivi with uboot. WHY?