It makes efforts to be kernel-version-agnostic; you should be able to use most kernels from most major distros. So yes, if you have a package that requires some special kernel you can probably just use that kernel. However, you will have to reboot to switch kernels like most distros - if you have two packages that each require mutually-exclusive kernel features, you can't use them both at the same time.

For example, the Fedora kernel has special patches for systemtap. You should be able to just boot into the Fedora kernel to utilize systemtap from a fedora userland package, but still get all your other packages from other distros, if you'd like.

"Any one that won't let Bedrock's tools and clients complain" is the answer - I know nothing about what the author's hinting wrt his future plans, but my impression's that the current release's a fairly light layer of mostly shell-scripted userland tools with only one needing compilation ("bedrock chroot"); Kernighan would be proud. (Those who treat the Unix Haters' Handbook as a source of design maxims would simply conclude a runtime built upon an introspectable and introcessionable language would obviate the need to marvel at the engineering involved here. The initial effort involved here, to be fair, is orders of magnitude less.)