Status of Multitasking in iPad2?
With iOS 4.2 and later, both the iPad and iPad 2 will allow multitasking by freezing apps in the background. Some things, such as playing music, will run in the background. Therefore, you will be able to do all of the things you want, but you will only be able to look at one at a time.

No, the SE sites do not look like that. I used the Develop menu in Safari to change the user agent, and it rendered exactly the same for the iPad as for the default view. However, it is different for the iPhone (still not the same as the page you linked).