Which is better for SEO?
home > page > sub page <h1> sub page </h1>
<h1> sub page </h1> home > page > sub page
The position of the H1 tag has basically no relevance compared to the content inside of the tag! A great descriptive text that reflects the contents of the page, is where the time should be spent.
Another far more important thing to keep in mind is, how do users react to the placement of the H1 tag. Is it more intuitive for them to have breadcrumbs above or below the Header?
also have a look at rich snippets, it is a great way to tell google which part of your site is content and what is navigation, and so on.
This doesn't really matter as long as you have only one
For example you should put your sidebar div at the end of the page, as the important keywords comes in the beginning of the page.