Honestly, I have never seen it work.

For me, it's just like any other badge, just for show, just to add to the credibility of the site which could indirectly affect bounce rates/sharing/etc.

Dont worry about the descriptions. It's just for additional info. I would prefer to have unique descriptions to maximize my visibility and relevance in Google's POV.

I did in my answer above.

If you want to totally solve it, also add a canonical to lead to a page that has ALL your posts shown. (Done manually, not through yoast)

You can just noindex those sub pages in Yoast under Titles and Metas

I would go 404's (and let them die) as I dont think those have any good content on them since it was just generated.

Redirecting them wont really do much.

There's really no way for them to enforce that policy unless a lot of people squeal about it.

I know here at Moz, it's really something like a Taboo, but it's really not. Big companies do this daily and they do it in bunches.

I would suggest though (since you mentioned that it's just a bitly link) that you just go for it IF the price is right and if it's targeted enough.

Look at it at the standpoint of getting traffic. You mentioned that it's a good site then it probably has a good spot for your link so it can bring in leads. If you can optimize to capture these leads or just get them to your sales funnel, then it'll be worth it. You'll get more links down the line.

It's pretty much like guest posting or paying for a best of the web spot.

Hi! Yeah, that's what i said. I would just ignore it and mark as fixed. Just be sure you crawl the whole site so that you dont have the old one linked on some page on your site.

Hi again Igor!

Those pages do not exist anymore right?

If you load them, they just show a 404? That's how I understand this since you moved to using a different plugin.

If your site's 404 page is optimized then, in my case, I would just mark them all as fixed and wouldn't bother with them.

I'll also make sure no other page is linking to those dead links.

As an alternative, I would export them, then do a redirect to the homepage. It'll bog you down if it's a lot so it's my last choice.

Hope that helps