This is all possible with open source Arduino hardware, and software. GPS, autopilot all possible with commercially available components. Why would it require heavy equipment? GPS modules are small.
You should start with Ruby, Rails, SASS for css, HAML for html, you should write your code in Aptana Studio, and deploy with Engine Yard or Heroku, Aptana has deployment wizards for both. Oh, and GIT for version control.
http://diydrones.com/profiles/blogs/ardupilot-main-page