I have a Dropbox installed and some doc files in it. I select a document and preview is displayed. When I tap "open with" (arrow on the upper right) I have an only one choice to open a doc file with AVPlayerHD.
Is it possible to send somehow a doc by email which is in my Dropbox?
Yeah, Dropbox does not let you e-mail a document straight from the app on the iPad; you have to first open it with a document reader app. Then, from that app is where you can e-mail the file.
There are a lot more apps in the App Store that will open/e-mail .doc files. For my setup, when I open Dropbox and select a .doc file, I get an option to open GoodReader ($4.99 USD), DocsToGo ($9.99 or $16.99), iAnnotate PDF ($9.99) or iCabMobile ($1.99). These just happen to be the ones I've got loaded... I tested it - all of these documents allow you to e-mail .doc files from within them.
So, all you need is one of these apps I've mentioned and you're in business! As you can see, they have a pretty wide range of prices. If you only want to do .doc e-mails, go with the cheapest (iCab - which is actually a very good web browser). But, if you want what some call the "Swiss Army Knife" of apps, go with Goodreader, as it can do so much more...
Good luck.
Marilyn