Kernel Newbie Needs Help

[Ed Sutherland <digital@twcny.rr.com>]

I've been trying to find the right Debian kernel for the iMac and have 
some questions.

Debian PPC (Woody) installs with 2.4.18 -- great networking, but it 
doesn't support the iMac's CRT: the left-most character of each line is 
hidden by the Mac's CRT black border.

I installed kernel-image-2.6.3 from www.pp.fishpool.fi, and it detected 
the iMac's hardware perfectly, but the networking support somehow was 
knocked out. My Ethernet (cable modem) connection via lynx and apt-get 
resulted in 'malformed URL' and other errors.

I went back to 2.4.24-ben1 and the networking returned, but the 
hardware support vanished (the missing character 'bug' returned.)

My questions:

1) Which kernel absolutely supports iMac hardware and CRT (ie, I can 
see the entire display on my monitor) while also providing networking?

2) What procedure should be taken before upgrading to a new kernel so 
that iMac hardware is supported?

3) How do I unpack and install a *.deb file downloaded via Mac OS X?

4) How do I return to 2.6.3 when apt-get refuses, saying it is already 
updated? 

Thanks a million.

Ed