Welcome to the Q&A Forum

Unless I'm mistaken, I think this guy was asking specifically about web directories like dmoz and botw.

There is a distinction between local directories and web directories—and the primary benefit of local citations has relatively little to do with links. The reason behind getting listed in either one is fairly distinct. Local has a lot more to do w/ establishing your address in the area + taking advantage of how sites like yp.com and Yelp take up a lot of space in SERPs.

It sounds like you're looking for these tools: http://moz.com/labs

Keep in mind that domain authority is Moz's metric. It's intended to predict how well your site might perform in search results. You might be able to rank just fine without a high DA.

To answer your questions as they are numbered:

1. It's possible. Low quality links are probably low quality because they lack relevancy and are low on trust.

2. Not necessarily. A natural link profile will have all kinds of links: some good ones, some decent ones, and some not so great ones. But at the same time, I wouldn't actively pursue low quality links. I just don't panic if a scraper links to me and start tearing my hair out over my domain authority.

3. Perhaps. Avoiding websites in "bad neighborhoods" is generally recommended. At the same time, you could probably spend your hours more effectively than reviewing everyone's link profiles.

4. I wouldn't avoid directories "no matter what." I wouldn't avoid anything "no matter what." Consider what the benefits are against the risks and go from there. With any directory, consider if it looks like a resource people would actually use. If it's just there for links, don't bother with it.

Just think for yourself with these things. Don't fall in love with bumping up metrics.

A few: Yelp is one, pretty sure CitySearch is another. FourSquare has done phone verification in the past.

I wouldn't really recommend you ever build a link network, but there is plenty of precedent for successful content networks. (e.g., buzzfeed, gawker, etc, etc.)

If you're doing it for the links, then give it up already because it's going to be terrible content and you're not going to be able to "build authority" as much as you think. The result will probably be you'll have 6 junky blogs that all get de-indexed in the course of a few months.

If you're actually interested in putting good content on them and building useful websites (and let the links land where they may) then it might actually be fruitful.

Put yourself in the user's shoes. (Keeping up with the shoe analogy...) If you were ordering shoes, would you want to see a pair of shoes listed out by individual sizes and colors every time, or would you rather have one page with all the options there.

I would recommend testing different approaches and seeing which garners a different response. Try using some on page surveys and see if you can get any response from visitors as to what they would improve about the site.

The last thing to consider is that the fewer items you have, the flatter your site is. The flatter the site, the easier it is for search engines to crawl it. Generally, deeply paginated results in ecommerce should be avoided.

I recommend reading this post from Distilled: http://www.distilled.net/blog/seo/common-ecommerce-technical-seo-problems/

And this one from AJ Kohn: http://www.blindfiveyearold.com/crawl-optimization

It could be any number of things. It's possible that you previously had links pointing to the site that were since deleted. Some link checking software will provide you with historical data, so you can see which links have been deleted over time. Won't recommend any here because that's competing software.

It could also be some kind of issue with Moz's crawlers. Maybe they haven't or can't crawl your site for whatever reason.

I wouldn't lose sleep over a hiccup in mozrank though. I would check on traffic data or maybe look at crawl reports from moz and Google WMT to see if any errors increased recently. If everything looks normal then I wouldn't worry.