I'd imagine that would be quite hard: many university libraries have their own proxies which make sure that visitors to the library are able to access the content that the library has paid for, and often modifies Google Scholar (with their cooperation, I believe) to list links to accessible versions of the content next to search results.

I don't know if they generally do, but I'm sure they can/will if they want to.

They don't block startpage and they've been around for a while.