"Force Quit" has a very specific meaning, which you may or may not intend here. There is a Force Quit... command in the Apple menu, which is used when the Quit command in an application's own menu fails to work. Is that what you're talking about, or are you using "force quit" to mean using the command in the application menu? The latter is not a forced quit, but the normal method of quitting any application (Command+Q is the keyboard shortcut for it, as Shootist has already noted).
You can prevent PP (and any other apps that are plaguing you at startup) from reopening every time you start up your machine, but not being a Lion user myself, I can't remember exactly how to tell you to turn that miserable "feature" off. Someone else will.
Whenever PP opens, it presents that centered window showing the assorted templates you might choose to use in preparing a new presentation. One of them is preselected, and if you close that window, PP opens the selected template, expecting you to go to work on it. If the next thing you do is to click on the red "Close" button in that second window, the second window should also close, without delay or protest. That isn't happening?