How to competently implement redirects for PS when transferring a site to another platform?

Question

Search engines

There is an old news site (age 5 years), with good performance in PS:

Pages indexed: more than 35 thousand. TIC: 650, PR: 4
The site is powered by Instantcms.

For a number of reasons, we are migrating our site to WordPress.
Naturally, the structure of URL links from Instantcms cannot be fully preserved and implemented on WordPress, hence the danger that something will fly out of the PS index + TIC indicators will decrease and so on.
Do you need the right redirects for PS? There are the following problems:
1) The link to the section on the old site looks like this:
http://site.ru/articles/articles/vlast
And on the new one it will look like this:
http://site.ru/articles/vlast
2) Pagination inside the section of the old site:
http://site.ru/articles/articles/vlast?page=2
on the new:
http://site.ru/articles/vlast/page/2
3) Link to a separate news (news page) on the old site:

http://site.ru/articles/articles/politic/byvshii-myer.html

on the new one:
http://site.ru/articles/politic/byvshii-myer.html
ps: The main problem is that WordPress does not support the creation of categories with the same alias (slug) for CNC, otherwise they would recreate all the necessary structure on the new site!

Answer 1

As far as I understand, you leave one article from the url.
Make a 301 redirect in htaccess
Something like this:
RedirectMatch 301 /articles/articles(.*) /articles/$1
Pagination needs more thought, but the principle is the same