Pageviews specifically...no. Popularity...yes. User experience is far more important though and Google's approach is based on sites giving users great experience and relevant content.

Google looks at h1 tags as clues to what the page's content is about. If you have multiple h1 tags with different keywords then it is difficult for Google to contextualize the page.

Best practice: one h1 tag with the keyword or theme you are trying to optimize for.

As long as it is in the section of your page. Crawlers look for tagging information in this section first so it may be missed if it is anywhere else.

If you are concerned about the amount of code in the top head section, you could move all that javascript into a external js file and reference it.

Agreed. URL A is now a higher authority page because of the proper canonical, which in turn means a link from URL A could have more value. But the equity from that link to URL B is not directly passed to your site.