How to install ClOD on new computer?

[DoolittleRaider]

I have a new Computer. I have Cliffs installed on my old computer, but haven't "flown" it in a year due to graphics card failure.

How do I install CloD on the new computer? Do I install it from my original DVD, using the same original Registration Key Code? Will that automatically connect me to my Steam Account?

I also have original DVDs and Key Codes for Shogun 2 and Homefront which are on my Steam account, so I have the same question regarding those games.

I have the same question for my two Call of Duty games at Steam (for which I do NOT have original DVDs any longer).

After I have Cliffs installed and recognized at Steam, how/where do I get the latest patch? Is the latest patch comprehensive, including all mods/patches/etc made over the past 18 months?

Any help/sadvice will be appreciated.