SEO impact of gradually changing design and text content

Question

I am working on a major upgrade of an online shop that includes both migrating to another CMS (page design will change a lot) and rewriting articles describing the kind of product that is sold. A couple of articles have notable SEO effect and I want to preserve it or at least not to vaporize completely. As I understand, these are the things that I can and should make the same on pages with rewritten articles served by the new CMS:

1. URL
2. <title></title>, <meta name="keywords">, <meta name="description">
3. The most SEO-successful sentences that are shown in snippets of search engines (there is a one such sentence in each article)

Another thing I consider is making a gradual updating of a website, so that I first put rewritten articles in the old CMS, wait for these pages being reindexed and then change CMS. Does this two-step process make any sense? Will search engines be less "shocked" because design and text content will evolve gradually?

Answer 1

It'll be better long term to update your page content slowly as you will be rewarded for constant page refreshes which contributes to domain authority.

To answer a few of your other questions:

1. Search Engines don't care negatively when changing the design of a website.
2. Search Engines don't care for meta keywords, they are obsolete for major search engines.
3. Search Engines love pages that have been updated content.
4. Search Engines prefer old URLS to have 301 redirects to new URLS, otherwise the rankings of the old page will be lost.
5. Search Engines love canonicals links, so don't forget to update these.
6. Search Engines prefer you not to change Titles and Descriptions if not necessary, if you do change them ensure they are relevant good titles.
7. Search Engines prefer the headers to remain the same but only if they are on topic, if they need changing, change em.