$50 on your Netbook isn't much if it means you hand your thesis in on time...
Selling advertisings isn't about creating new places to put ads--it's about making advertising space more valuable. And that isn't as straightforward as you seem to think. :)
* And adsense ads in apps that others create.
Release an OS that will drive traffic to your spreadsheet app that will drive traffic to your search engine where you can sell ads.
*Gmail still doesn't really makes much money.
Not far removed at all. Google makes billions by selling ads. Even if they budget a couple of million $/year for this project (might be less, depending on how you structure the proejct), they'll be making crazy returns if this increases their ad revenue just by 0.001. Not to mention all the FUD it'll cause inside MS :)