newbie needs help in mapping counties in color

[Ravi]

Hi Guys,

I am a newbie and need a very simple application. I am sure mapserver 
(and kamap) support it out of the box. I just need to be pointed in 
right direction. I have been working on this for 10 days, so I have some 
idea of mapserver now.

I need to show a map of US streets with each county colored differently 
based on the cars/household density. If you zoom in to a state level, 
then map should color each "block group" rather than each county. That 
is all I need. Here are my problems with this:

1. How can I convert TIGER street maps to shape files? I was able to 
find commercial version of these files but without geocoding data. Since 
I need geocoding data (to provide ability to zoom to an address), should 
I encode the data myself to shape files? If so, how can I do it, just 
some pointers would be very helpful.

2. Also, I put each county file on a separate layer and that works fine 
but I do not think that is the right way to do it. Can I put all 
counties in one layer? If so, how do I do it given that there is a 
separate shape file for each county? If I join the shape files, how can 
I color them differently?

This is all I need. Any pointers, help, prebuilt "map files" etc. would 
be very helpful.

Thanks a lot for your help
Ravi