Just bought GotY edition, and 2 questions...

High, I just bought and started the Game of the Year Edition. To my knowledge, it has all the downloadable content to date, minus a couple that were release after it.

Questions:

1) Do I need to install a recent patch, or does it do this automatically because I am on Steam?

2) I took a peek at the scenarios section, and it looks like I only have 4 scenarios. I thought I should have a lot because of the downloaded content included? Am I missing anything to "unlock" these other scenarios, or are there really only 4!?

Thank you,