Make edits to the Bitrix website

There is a site on Bitrix that needs a list of edits that the CEO has put.
For example, set up an adequate display of a page with a 404 error, configure the main mirror of the site and redirects, fix errors in css and html, optimize the weight of photos, etc., a total of 10 points of edits, everything is in the form of a detailed list with a description.