The easiest way to accomplish the first three is to provide an actionSet, added to a new top-level menu and also accessible from its own toolbar.

完成前面三步最容易的方式是提供一个 actionSet ，它被添加到新的顶级菜单中并且可从它自己的工具栏访问。

youdao

To answer your queries, loading time from the live tile menu to the top tweets page above is approximately three seconds, while scrolling is basically identical to the perfection available on WP7's own apps.

ENGADGET: Official Twitter app for Windows Phone 7 goes live (update: hands-on)