1) You can use respond.js[1] if you don't need complicated media queries. It's much smaller than 15k
2) Icon Fonts should make use of the Unicode Private Use Areas[2]. Screen readers should not attempt to make sense of these code points, and you can add title tags to enhance accessibility.
On #2, that might fix screenreaders but it still looks ugly if a user chooses their own font: https://f.cloud.github.com/assets/1126981/506313/554bfab4-bd...
What we're likely to do is to create SVG icons and use those. with .png fallback... much like how Zurb are doing so: http://zurb.com/playground/social-webicons