Yes it will - the code will be run for every page in which the footer.php is included.

1) Yes definitely having a link to your site from high profile social sites like facebook and twitter will help you get indexed by the search engines. One way to help google discover other pages of yo ...

I personally think it's better at the bottom.

The reason? Because it takes time to execute, I had a problem on a website a while ago (a couple of years, so maybe this isn't an issue now?) where my ...