I haven't compiled a list of documents to support my response - just relating to you more my experience having switched from a niche product to one more main stream. So my response was more personal opinion and experience - not fact or documented research. Hopefully I raised some issues you hadn't thought about before.
In dealing w/ the Word questions. It is possible to create a document library that uses a Word document template as it's foundation for new documents.
So - let's say my company has defined a proposal template in Word. This template has a preset definition for the font to be used, has my company logo on the front page, has the standard legal disclaimer page saying the proposal is only valid for 48 hours from receipt, a standard table or grid where product number, description, quantity and price are layed out etc.
Now, my company requires that all proposals be based on this template. And that all proposals be stored in a Pursuits library on SharePoint.
So I could do one of 2 things. I could distribute this template to all sales staff and their assistants. Have them install it locally on their machine, and when it's time for them to write a proposal, the create a new document in Word, based off that proposal and trust that they will upload it to the Pursuits library. When I have changes to the template, I would make them, and have to send out a new, updated template to everyone who uses it, hoping that they are able to install it correctly etc.
OR...
I could create the Pursuits library - and upload the Proposal template to that library as the template new documents are based off of. Doing that, when a new proposal needs to be written, you would navigate to the library, click [New] in the library toolbar, and a new document would be created based off that template. The proposal is completed, and as part of the save process, the proposal is uploaded automagically into the Pursuits libary.
If I have a change or update to the template, I would make it, and then upload the new teamplate version to SharePoint - secure in the knowledge that everyone creating new proposals in that library would be using the new template.
This same scenario would apply to a standard template for other office products as well. In fact, we have a standard Powerpoint template, w/ copyrights, standard fonts, company brand and colors predefined - using the same scenario. If someone wants to make a new powerpoint presentation - starting w/ the template loaded in a document library ensures that they maintain our brand requirements.
Another example of the kind of integration SP has w/ Office applications - when you create an email, and then go to attach a document to it - Outlook will give you the option of sending the attachment, or just placing a link to the file in the email - so recipients can just go to the appropriate site on SharePoint where the file exists.
Email load for us has dropped significantly, and - because of the way the link works - you are always assured of getting the most current version of the document when you click on it. No more sorting through your emails - trying to impose version control via the sent date on an email message.
Now this only works if all recipients are internal associates. If you are emailing to a client, chance are they won't have the permissions to access your intranet via the included link.
Hope that helps.