iso images etc

[john gennard <joney@clara.co.uk>]

I have become interested in the creation of a personalised distro.
'Gentoo' was on the CD which accompanied my monthly Linux Magazine,
but this only contained tarballs for 3 stages. After asking around,
I was referred to 'Linuxfromscratch' - its literature is very
detailed and after reading it two or three times I'm beginning
'to see the light' (tongue in cheek!!).

Sometimes I have access to an ADSL line, so I have downloaded an
.iso image of Gentoo. Now, I realised that I didn't understand
exactly what an .iso image was, so I've googled and now have that
a little clearer. But what I don't understand is how to boot the
image I've downloaded and I find no clear explanation.

I've found a Windows program called 'undisker' which allows me to
see what is in the image. Briefly it contains two folders, one
named 'gentoo' which holds bz2 files for the three stages, and
the other named 'isolinux' which contains files which have to do
with booting (some of the .msg files are readable as text), plus
a file named 'livecd.cloop' (35+Mb) - google tells me this is
'compressed loopback filesystem support'.

I burned the .iso image to a CD, but to make it bootable, I was
asked to add the contents of a floppy - presumably containing
drivers to activate a CD-ROM drive. I couldn't do anything about
that, and if I change my BIOS to boot from a CD-ROM it doesn't.
I thought the .iso downloaded was bootable.

Would someone kindly explain (in simple terms):-

1. How to I get the CD to boot?
2. Is there some special reason to use the cloop - would
        some other form of compression not surfice?
3. Is there a linux package which allows one to read
        and extract files from an .iso image.
 
Thanks,                 John.