As per knowledge DA information updates near around every month but I don’t think there is any tool that records the history of Domain Authorities over the period of time.

At least not in my information!

I never say No to it, unless you have like 20 domains 301ing to the main domain but one or two are fine in my opinion.

When buying an expired domain, having a decent DA is not enough, also check their links that are pointing the website and if they are fine, go for it otherwise, 301ing the domain to the main domain might hurt!!

In my opinion, if you are going to use the main domain that is blogspot.com it will probably disavow any link that is coming from blogspot.com which means if later down the list if you get a good link from the blogspot, even it will not give you any help!

In my case, I used the sub-domains and it worked fine for me!

Hope this helps!

If I would be at your place, I would have checked the links that are pointing to the old URL and see if the links quality is good and will help the new domain, I would have done the page level 301 redirection. If for some reason the links are not helpful for the new website, I would have done the page level redirection until the old pages get removed from the Google index and new pages get crawled.

Once this happened, I would have reduced the redirections to only one that is domain level redirection and this is to let the audience move to the new website.

P.S: Using Change of Address Idea by Mike King sounds powerful to me!

Ok, Here there could be two things, eaither the CMS you are using is keep generating suplicate content which is why this duplicate content issue rise again or someone have made some changes in the website which remove the chacnes done by your developer.

Hope this helps!

I agree with Peter, I have worked with a company who had several different products that are huge so they used the similar structure. I think in order to give better user experience they should have some text on home page (instead of image only) but i think from the technical SEO perspective there is no big problem with this!

I never heard that Google use any specific version more important than the other one but as a user I would advise you to use one format so that when user land on your page they see a single format though out the website.

I personally don’t think this will impact rankings in any way!