Welcome to the Q&A Forum

Sorry missed the bit about blog.
obviously blog.domain.com should not 301 to www
it should point to the correct site, then all reports and google will sort themselves out.

so add one more step, test that blog does in fact resolve to the correct site

You need to point your cname to the ip of the server that hosts your sales.domain.com

don't

sales.domain.com > domain.com

Do

sales.domain.com > 123.123.123.123

where 123.123.123.123 is the ip of the hosting webserver.

Test that non-www 301's to www
Make sure that all your internal links point to www, you don't want links that you control going thought a redirect.

If those 2 are ok, then forget the report it will sort itself out over time.

Yes correct, I was talking from a purely SEO perspective

this is simple. rather that test what the domain name is, test what it is not.

use the logic,

if not my-preferred-domainname then redirect to my-preferred-domainname.

this of it like this, all roads lead to Rome.
To the search engine its like following a sign saying elevator, going into a room and seeing another sign that says elevator and so on, until your in the elevator and no more signs to follow, they think well this must be it. The page you want to rank should be the final destination, link from one page to the other with relevant link text, but not back again

no problem at all with google.

The only problem I see, sending link juice to SiteA from SiteB.
To the search engine its like following a sign saying elevator, going into a room and seeing another sign that says elevator and so on, until your in the elevator and no more signs to follow, they think well this must be it. If your page is about dogs, you don't want to link out from your page to another page about dogs.

I don't know what you mean about link equity, if there is no link pointing to the page then there is nothing lost.
As for search engines finding a lot of 404s, they will remove them from the index after a while, no problem there, you are returning the correct status code, that's what they want. This will allow them to clean up there index and stop crawling the pages.

One thing more I would add, there may be a reason this domain has expired, it may be that it has a penalty, you maybe inheriting someone else bad reputation.
I would not bother.

I would say that you have either made and error or it is coincidence.

BUT there is one other possibility, imagine google sees your site is about The Rolling Stones, it has the words rolling, stones, rock , but you then mark it up as a site about geology, the search engine may no longer rank you for the musical rolling stones.
In your case it could be more subtle than that but you get my meaning

do you know if they had any external links?

If they don't have external links then I would just let them 404.
some people have some wired thoughts of what 301's do. They simply redirect a request, so a request o A is told to remake the request to to B, so the crawler will follow it that way and award the pagerank to the new page with a small loss on each request.

If no external links what is there to gain? don't complicate your site with unnesasary redirects, there is a small argument that the pages may have been bookmarked at old url, but I think that argument is so weak I would not bother

I cant see B working, I don't think you will have any success contacting webmasters to do as you asked.

but A, may not work either. I don't know what google does with expired domains, but if you think as a search engine,  would you want to awrd link juice from an epired domain to someone that buys it for those links. If I owned google I would tell me programmers to find a way to stop this happening.

sorry Matt I don't understand why you would want to ping the links, the links will be followed by the search engine in time, what would pinging tem do?

No, no-follow links still leak link juice, it just doesn't reach the others site., if you no follow. it would be like, I give you 10 dollars, you throw 10 dollars down the drain.
Really you don't want to link away from your site, unless needed

Here is an old article I wrote on page rank, old by still relevant. http://thatsit.com.au/seo/tutorials/a-simple-explanation-of-pagerank

David is correct, it can look like link farming. but only if you do it a lot.
but the bigger concern is that you are pouring away link juice. Its like I give you 10 dollars and you giving me 10 dollars, where is the gain?

I don't quite agree with Bob. If you have a hand made site it is easy to implement schema.org, but if you have a cms it varies, I know some cms have implemented schema.org and in that case its quite easy, if they haven't it may be hard to edit for a number of reasons.
but I always think you can do a lot more if your site is hand made where you have full control.

That's depends.

Visitors to your site have fonts on there computer already, using these fonts will give you the best load speed, you can look up "web safe fonts" to find these.
Using non web safe fonts means downloading font objects, now wether these are downloaded from your web server or from google they still have to be downloaded, if you have a fast server it may be better to host the font objects yourself, if not you may be better downloading from google.
Me myself, if I use non web safe fonts I like to host them myself, I don't like having any third part resources on my sites.
Thanks

Press F12 in your browser and use the network tab you will not only get your load time you will get it broken up so you can see where the problem is.

Bing did a study on load times, and every 10ms worked out to cost the average ecommerce site $200+ a year. What is an average ecommerce site, I am not sure, but it tells you something.

Keep them or remove them, don't redirect them unless they have external links, you want to keep things simple,

if you do remove them. make sure you remove all links pointing to them from your own site, you don't want broken links.

They turn me off,

sitemap does not ensure you are in the index. they just inform the search engine about your site.
in fact Bing suggest you only put hidden pages and important pages in sitemap.
IMO they are overrated unless you have something special to inform them of, or a very large site , they will find it crawling your site normaly