2. Does Google search PubMed?

Yes. Google and Google Scholar both search some of PubMed, so you'll find PubMed citations in your Google results. But, due to Google's page rank formula, PubMed citations often appear at the bottom of your results. Also, Google Scholar is up to several months behind PubMed and doesn't search PubMed in its entirety.

Bottom Line: Google and Google Scholar can be a quick and easy way to get started on a search. However, they do not comprehensively search the peer-reviewed biomedical literature. PubMed does.