So, what an iPad can do, is everything you've stated except (for what I know) basic web dev. You could go to docs.google.com and write long documents and the screen is ideal for reading and Safari on the iPad is phenomenal.

A netbook is most likely a better choice for what you want to accomplish. A physical keyboard makes writing long documents trivial, and you get access to a terminal for your web development.

The iPad was made for recreational use, basically for 'having fun', playing games, going on Facebook, ect.