nope the education discount is probably the best option, the next best is probably buying an OEM version they are typically a little less than the retail version.
yeah opera mini and opera mobile are very different, opera mobile is an actual full browser where as opera mini is actually doing the rendering of the page in question on opera's servers and displaying the results.
yeah just get him a cheap pair of headphones to use.
otherwise why not just change the password on the router so he can't go in and undo any blocking you turn on?