On my browser the page returns a 302 (temporary redirect). It could be that MOZ would still expect the page to eventually resolve. A 302 usually means that the page is temporarily down or not available. Thus should keep the page in index as it should eventually re-appear.

If you are not planning on making this page available again I would suggest you use a 301 instead.

I tend to use this quite a lot; It does not harm Search Engines, what is important is that only inline elements are contained within an H1 tag, that is span is a perfectly valid element, however a div is not. In your case you should use multiple spans with separate class names.

You should also consider splitting it into H1 / H2 depending on your site structure and navigation as it might make more sense in some cases.

I would say no, importance is related more to the content then the fact of a page being a home page or no.

I would even think that for stuff like keyword in url, an internal page could be much better to optimize then the homepage. The homepage should give an overall picture to describe your enterprise. main keyword here would be your branding keywords to make sure you're first for your brand name.

I would then use internal pages for better optimization of the text, and SEO for the various terms. This way your page would be about the term rather then just mentioning the term - should be more relevant to the user / reader.

Yes and no;

The root domain usually tends to get far more links then your inner pages, as any links about your website / brand usually come in here. Should you target keywords on the root; it would benefit from having the increased in-links.

The result would then depend on the level of on-page optimization that you are able to do on the home-page or internal page. Usually on internal pages you can control far more the content and thus make better on-page optimizations, should the levels of optimization be more or less the same I would safely assume that your home page (root) would take prominence.