How to translate a Wordpress theme into Russian?

Question

Internationalization and localization

Good afternoon or good evening, dear community!
How to localize a topic into Russian? Here is the theme
itself And related questions:
1) Is it possible to translate the theme into Russian from the admin part of Worsdpress?
2) How to check the topic for errors, site and links to resources?
3) How to properly optimize Wordpress for cache?
4) Faced with the problem of limiting "headings" in Wordpress, or is it a limitation in the topic itself, I don’t understand. How to remove this restriction if there are more than 50 headings?
Thank you for your attention.

Answer 1

using poedit

Answer 2

Here is a plugin that allows you to do this from the admin panel https://ru.wordpress.org/plugins/loco-translate/