Linux kernel headers

[booleandomain]

Hello,

I have some doubts about the following configure options: --with-headers,
--enable-kernel.

First: does really glibc require linux kernel headers for a successful
compilation? That is, can I specify something such as --without-headers?

Second: if I specify --with-headers=$PATH can I delete $PATH directory after a
successful build?

Third: can I specify --enable-kernel=2.6.30 even if my host os run version
2.6.29? or should I stick to 2.6?

Thanks.