Can I use Android Emulator to get the Free apps from Amazon's app store? It is said that we can test drive using Android apps even using an Web based android emulator for Amazon, but I don't see it on Amazon's Angry Birds webpage?

Can we download the Android SDK and use the emulator to use any free apps offered on the Amazon app store?
You can certainly install the Amazon App Store app on the emulator.  First go to the settings and allow installation of apps from unknown sources, then open the browser and download this app.  This will download the app store .apk, which you can then install.

However, if you are planning to download and run Angry Birds (or other games), on the emulator, you will probably find it is too slow unless you have a very fast PC.  It might work OK for less demanding apps.

Also, beware that at the moment Amazon only permits US users to download apps (see How can I get apps from the Amazon app store from an unsupported region?).