Welcome to the Q&A Forum

Marketing and success are both in the url, so having a / or a - isn't going to be the final determinant on how you rank.  The thing I'd worry about is "marketing/success" implies marketing has greater importance than success, in the root scheme of things.

If it's the category that the items on the page fall into, probably not.  If the inserted keyword leads back to a page outside of the category, it may be a little spammy.  From what I understand, breadcrumb produces codes based on where the viewers was on the site, so if the inserted code looks like all the other dynamically produced html, I don't know how G could distinguish that, other than it doesn't fit the content on the page.

I've got 100s of new pages over a year old, all with quality content, yet they're all still at PR0.  The main index page has a PR score of 4, yet all the other pages of the site are still at 0.  They're are all unique and highly relevant pages.  Anybody else notice Google's taking longer to rank pages?

Why is Google taking so long to update PageRank?

The 301 from the old domain is going to carry good and bad juice over to your new URL, consequently I think your doing the logical thing by trying to eliminate as many of the bad links as possible.  If you remove, the 301's, you'd be starting from scratch.  Since you've initiated 301's I'd hold your course, and start building new links to the current url.

You should try to mirror the 301's to the duplicates on the main site.  So in answer to your first question, the duplicate blog index page should go to main/blog, and everything else should go to the new location on the main site.  Anything without landing pages on the new site, should redirect to main/blog.

Sounds like you've got a php site that's dynamically creating pages.  You have to find the person who wrote the script and have them edit the template to add a canonical tag that inserts the correct url when the page is generated.  Your not going to be able to insert a static canonical tag.

Option 1 is a very good idea if you think these links will hurt you, Google wise.  Since you says these are all duplicate content, this is probably what you want to do, but first be sure you don't want the link or authority juice from the old blog.  If the blog gets more traffic, has more authority, etc...the decision gets tougher to make.

I do think NoFollow is more pertinent for external sites linking to your site, and not so much inner site links used for navigation.  I'd be more concerned with the amount of keywords used in the metatags.