There is nothing wrong with unlisted pages, it is even recommended for any content behind login screens or procedurally generated pages like carts.  If something it not listed, Google will not see it so it will have add no value to your site from a search perspective.

Set up Canonical tags and use Google's UTM codes to track your non-internal links (as your internal links will be tracked just fine by Google Analytics without any need for using redirects).

https://support.google.com/analytics/answer/1033867?hl=en

https://moz.com/learn/seo/canonicalization

That sounds rough.  What you will want to do is alter your content for your single city based website to reflect that you serve that city, then when Google is looking for a match for a person near that city, it should see that site as the best match do to the weight it puts on geolocation.  In the long run, you will want to re-write all of your content on one site so that your two sites will not be hurting each other or look like copy/paste spam sites.

You should find the locations of those links and correct them to point to the proper URL. I find that Screaming Frog's crawl is the easiest for this, you can find every link and see where they are located.

There are 2 parts of your robots.txt that could be causing this, and it all just depends on how each bot is reading regular expressions in your robots.txt:

First, your Disallow: /? can be read as Disallow all paths starting with "/" with 0 to infinity characters "" and one character "?". Try replacing this part with Disallow: /*? to make it not crawl anything with a query string (which is what I believe you were going for).

Second, you have a open Disallow followed by the User-agent: rogerbot and while this should not be read this way, once again it all depends on how each bot reads the commands. To fix this you should change your Disallow following your Googlebot-Image as Disallow: /

If your content cannot be seen without logging in or getting past a "gate" then in general, Google will not serve people to that content.  If you are planning on trying to spoof it so that the Google bot can crawl the content but people cannot see it, don't, Google will find out and then at best you will just see all of your rankings tank. Google wants to searve people the best, easiest content that will give them what they are looking for so if you are not openingly providing that content then Google will not send you traffic for those queries.

This is generally normal for most industries, less people are on computers on the weekends so you see a decrease in not just search, but overall traffic. The same thing occurs any time you have a holiday during the week (Thanksgiving, Christmas).

IT will really depend on your area and the language your customers use.  I have seen the same CTA wording, in the same region perform both amazing and far below expectation, and it had to do with what the end product was and the language that people in the area used when looking for those services.  Your best bet it to run an A/B test yourself and see which CTA responds better to your potential customers.

It could, but it also could help your ranking.  The amount of text is not important as much as how relevant Google sees it compared to the search query, so if you are removing superfluous words and redundant passages they you should see an increase as your pages are more user friendly. If you remove good copy that was considered helpful then you would expect to see decreases.

No, you should not be stuffing KW or worried about density, make your content user friendly and useful based on the KW phrases that you want to attract visitors with.