Installing in a sub-folder for development

I am setting up a WordPress site for a cust. who has an existing HTML site at (say https://examplesite.com ). Obviously I do not want to disrupt the site while the new site is under development.

The following are the steps I have been given to set up WordPress in a sub-folder for development (let’s say https://examplesite.com/wp/ )and then make it available at the root level. Can someone please confirm I have the following info correct:

1. Create /wp sub-folder and install WordPress
2. Settings->General for WordPress URL: https://examplesite.com/wp/ and for Blog URL: https://examplesite.com/wp/
3. When ready to go live and make the WordPress site available change the Settings->General for Blog URL only to: https://examplesite.com/
4. Put the following index.php file in the root:

<?php
/* put this file in root folder */
define('WP_USE_THEMES', true);
require('./blog/wp-blog-header.php');
?>

5. Question, in #4 above do I need to change the /blog to /wp if I have the install in a /wp folder?
6. Update permalinks at Settings->Permalinks (Question – does this process change an address such as https://examplesite.com/wp/about to new https://examplesite.com/about ?
7. delete or rename the old index.html from the root
8. redirect old html pages to corresponding new addresses

Does this look accurate?