@JD Collier: Thanks for your reply!

1. Accessibility does look reasonable in the latest Foundation. I'm going to have a more in depth look before committing to it though. At a glance it looks better than bootstrap for accessibility:

bootstrap: https://github.com/twitter/bootstrap/issues/search?q=accessibility
foundation: https://github.com/zurb/foundation/issues/search?q=accessibility

2. Using chrome frame sounds good/tempting.