Trouble with apt-get

[Dororthy over the RGB]

Hi people,

I'm having some trouble with apt-get.

I downloaded YDL 3.0 (CDs), installed it on an old Mac. So far, so good. 

The first time and all consecutive times I tried to run apt-get update, I've 
got some errors or warnings such as:

"...
W: Release file did not contain checksum information for 
http://ftp.yellowdoglinux.com/pub/yellowdog/apt/3.0/base/pkglist.main
W: Release file did not contain checksum information for 
http://ftp.yellowdoglinux.com/pub/yellowdog/apt/3.0/base/release.main
W: Release file did not contain checksum information for 
http://ftp.yellowdoglinux.com/pub/yellowdog/apt/3.0/base/srclist.main
W: You may want to run apt-get update to correct these problems
..."

Note: I unfortunately did not keep the messages returned the first time.

After the first call(s?), I updated /etc/apt/sources.list with the one at 

http://www.yellowdoglinux.com/apt/sources.list

Then things started to get rather badly after the apt-get -f install.

--> History of the calls I made

  335  apt-get update
  351  apt-get update
  353  apt-get upgrade
  366  apt-get check
  367  apt-get -f install
  368  apt-get check
  380  apt-get check
  383  apt-get clean
  384  apt-get update
  730  apt-get clean
  731  apt-get autoclean
  732  apt-get check
  733  apt-get -f check
  734  apt-get check
  735  apt-get update
  736  apt-get upgrade
  737  apt-get -f upgrade

--> Currently, apt-get check spits out what follows:

"...
  zsh: PreDepends: /sbin/install-info but it is not installable
       PreDepends: /bin/sh but it is not installable
       PreDepends: /bin/sh but it is not installable
       PreDepends: /bin/sh but it is not installable
..."

For most of the packages.

--> apt-get -f upgrade says it will remove most of the packages and ends up 
with the prediction of a looming disaster:

"...
3 packages upgraded, 0 newly installed, 1305 removed and 0 not upgraded.
Need to get 1545kB of archives.
After unpacking 4175MB disk space will be freed.
You are about to do something potentially harmful
To continue type in the phrase 'Yes, do as I say!'
..."

My understanding is that apt tells me that everything is wrong while the 
system work OK, so I guess I definitely screwed up the dependencies one way 
or another. Anybody with ideas to get me out of the pit?

TIA.