no, it will not hurt motoblur if you use a replacement launcher, as replacement launcher are essentially just apps that you are running over your stock launcher. if you decide you want to use one of the third party launchers as your main launcher, go back to your stock launcher first and remove any shortcuts and widgets you have on it, as the stock launcher is still running in the background.
launchers do delete when you uninstall them. again, above all else, they are still apps like any other.
the 2 stars in the dockbar on adw are customizable icons. all you have to do to put your dialer in one of them is open your app drawer, longpress on your dialer app, and drag it down to the dockbar