Help! me with site

Hello. Tell me, the situation is the following: there is a simple website for online blackjack real money Canada, made on the “designer”, you need to transfer it to Wordpress CMS, but for the domain to remain the same (the domain was purchased separately and does not belong to the designer). Having found and read available, few information (08-16 years) on this issue, several conclusions emerged.
Do I understand correctly that:

  • You must first transfer all content and sections from the “designer” to the new site, even if some sections are not needed. At the same time, to url pages on the new site, coincided with the url of similar pages of the old site, or make a 301 redirect to redirect all pages of the old site to the corresponding pages of the new.
  • Transfer links, colors and styles (!) To pages from the old site.
  • Move meta tags (title, description, keywords) for all pages and sections of the site, even if they (meta tags) are no longer satisfied.
  • Accordingly, all pages set Titles exactly as on the old site.
  • Change DNS server.
  • Create a new sitemap file and robots.
  • Transfer statistics counters, webmasters.
  • New features, sections, and articles to add to the new site after everything is indexed.

The goal of the actions is to prevent the domain after the manipulations from disappearing from the search index. Tell me, please, are all actions relevant and obligatory at the moment, or can some be roughly neglected? Maybe, on the contrary, some of those not described above are vital? Maybe you can not bathe, make a website, push articles into more suitable sections, add the necessary functions, sections at once, and everything will be fine?