301 redirects are called permanent, but that's not really the case. They are permanent only as long as they are in place. If you want to see this, do everything as Andy said and then remove the redirect. You'll notice your traffic drop and when you put the redirects back the traffic will recover. Go ahead and do this every year and you'll see that each time it drops. We've dealt with drops that happened from domains that haven't been active in over 5 years, so as EGOL alluded to, keep them forever.

Sounds like you rank for a lot more terms on desktop than mobile, and probably not as well for a lot of those terms. In addition, it could be that a lot of the mobile searchers are in your area, which tends to make you rank higher because of the localization.

I'm not sure if this has been fixed already, and thank you for Dan for chiming in, but I was able to crawl around 700 URLs.

As L Slversen said, your Google Analytics tracking code is missing so you wouldn't be recording traffic. This probably happened with your theme changed and likely the traffic you are still seeing on the site is not legitimate, more than likely ghost referral spam traffic.

As Bob said, these porn spam referrals are just the latest in what looks like it will be an unending fight to keep your analytics data clean. We keep our list fairly up-to-date with the latest spam referrers if you want to try to filter them before they show up in your account.

http://www.theedesign.com/blog/2015/blocking-spam-referral-traffic-google-analytics

Sometimes this is done unintentionally, and there may be no ill-intent. Either way, one should be properly redirected to the other.

import.io and it's free

Doesn't have to be so tedious. If you have a list of URLs you can use the bulk removal extension for Chrome found here: https://github.com/noitcudni/google-webmaster-tools-bulk-url-removal