Can local WordPress installs share /wp-content/ folder and database?

For wp-content folder you need to add WP_CONTENT_DIR with path to this folder to each wp-config.php file of each your sites. All of these WP_CONTENT_DIR constants should have the same path to one folder. Read more about it here: http://codex.wordpress.org/Editing_wp-config.php#Moving_wp-content

To share the same database, you just need to setup the same database settings in each wp-config.php files. Read about it here: http://codex.wordpress.org/Editing_wp-config.php#Set_Database_Name

UPDATE: To make your urls work correctly define WP_SITEURL and WP_HOME constants which will override options settings. Read about it here: http://codex.wordpress.org/Editing_wp-config.php#WordPress_address_.28URL.29

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