How to move pages to another url?

Question

Search Engine Optimization

There are pages like:
site.ru/folder1/page1/
site.ru/folder1/page2/
site.ru/folder1/page3/ I
transfer to:
site.ru/folder2/page1/
site.ru/folder2/page2/
site.ru /folder2/page3/
The essence of the transfer is to make the url informative and at the same time short.
All pages in the top - 1-3 places (Google), 2-8 (Yandex)
Main 3 questions:
1. Doing a 301 redirect, right?
2. Do I need to close old pages from indexing immediately after the transfer?
3. Will the positions sink?
Need to do something else? (sitemap.xml updated, search engines in the webmaster informed about new pages)

Answer 1

1- true
2- no, not necessary
3- hardly, but theoretically there is a chance. They will return.
You have done everything and plan to do it right. Nothing more is needed.