iPad as a productivity tool?

Hey Apple folks, I'm hoping you'll be able to help me out.

I'm considering getting a new laptop since I travel a lot for work and I want something thin, light, functional. I'm not really impressed by any of the Windows 8 offerings and am kind of a Mac person anyway (I've got a MBP from 2008-2009 as my personal machine). So I'm considering an iPad with the ultrathin Logitech keyboard.

My problem is that I have serious doubts that the iPad can really be used for productivity. I owned one of the original ones and ended up getting rid of it in frustration over its lack of ability to do what I thought were some pretty basic tasks. But every time I go on the road I see them everywhere, so I thought I'd look into it again.

In your experience, how would I do the following tasks (which are all pretty much deal breakers):

  • Download a spreadsheet from an email, make edits to it, and resend it on the same email thread.
  • Open a Word-compatible document to view comments and track changes.
  • Organize, open and edit files for a website (basic html coding and image files)
Any thoughts?