If I understand your request, I think you want to customize the TinyMCE toolbar so it doesn't show the "paste from word" button. Go to Dashboard -> Sitewide Settings and change the "Rich Text Editor" (or "Rich Content Editor"? can't remember the exact name) to "Custom". Now, you'll need to learn how to customize TinyMCE's settings, which is a bit confusing to say the least -- but search the forums here and you should find some helpful posts (and also you could just google for "customize TinyMCE buttons" to find more details that aren't specific to Concrete5).

Not exactly. I *wish* they would use the Paste from Word button. Actually, I wish they would not paste from Word at all, but that doesn't seem to be an option for some people. It would be nice if all the stupid formatting wouldn't transfer, but it does.

I did a quick google search and came across quite a few promising leads (but they're all specific to TinyMCE -- you'll have to figure out where exactly to place the code within the context of Concrete5):

http://www.thismuchiknow.co.uk/?p=44...
(this one looks like it forces the "Paste From Word" option even when the button isn't clicked)

http://www.chrisrossi.com/2011/01/14/how-to-remove-font-styles-in-t...
(this one looks like it lets you disable specific styles or tags)

There were a bazillion other results too -- looks like it's definitely doable, although it will require a bit of work on your end. If you figure it out it would be great if you could post the results back here.

Best of luck!

-Jordan

Ironically enough, jordanlev's own Designer Content block has helped me really lock down the styling of the content for a site with specific layout needs. I just created a block for each type of data and then specified permissions for the appropriate areas to only allow certain blocks, and viola -- user-added content with controlled styling!