See Codex for running a development copy of wordpress. You can make all the changes you want on the blog without affecting the production site by testing out new themes/etc which is what it seems like you’re looking to do. http://codex.wordpress.org/Running_a_Development_Copy_of_WordPress#WordPress_2.7_-_3.0
use WordPress export option and after that use import on the second site How to Export and Import a WordPress Blog
The wp_posts table has a guid field, which should be globally unique, and survive migrations. It is formed by taking the initial post URL, and never changed after that (when you change the title, change the website address, or migrate the posts). This should be pretty safe to base your synchronisation code on.
I use the plugin Duplicator. This will copy all files and databases in one package, migrate the databases,… You can even set up filters to exclude/include certain files. It takes 4-5 minutes to migrate everything to localhost and vice-versa.
See Moving WordPress « WordPress Codex These are typical queries to run in phpmyadmin to change URLs, but you may also have serialized data in widget and theme options that will have to be changed, too: UPDATE wp_options SET option_value = replace(option_value, ‘http://olddomain.com’, ‘http://newdomain.com’) WHERE option_name=”home” OR option_name=”siteurl”; UPDATE wp_posts SET guid = replace(guid, ‘http://olddomain.com’,’http://newdomain.com’); … Read more
In addition, you can import attachment by checking the “Download and import file attachments” option. (source) This means, if you use the official WordPress Importer plugin, it will read the media URL from the file, download that file and finally upload it to your new install. When your old site is offline, eg. taken offline … Read more
** Edit ** Did you check your folder structure ? did you rename the wordpress folder ? have nested folders ? ** end edit ** @ allan z – that will not (always) work for an existing site , due to a multitude of reasons . the best way is to either follow these instructions … Read more
Read http://codex.wordpress.org/Moving_WordPress#When_Your_Domain_Name_or_URLs_Change You’ve only moved the PHP files. That is only part of the process. Migrating the databse would mean: Create a database, if there isn’t one already Move the database from your local server to the remote one. Edit/alter key values in the database The same wp-config editing trick used here will get you … Read more
I use this for search and replace on databases – https://interconnectit.com/products/search-and-replace-for-wordpress-databases/ Simply move files with FTP, export and import database and then run the script searching for old URL and replacing with the new URL. Then I resave permalinks and I’m done. I’ve moved WP thousands of times using this. I’ve got the old script … Read more
You can use the WP CLI too to rename your site’s hostname safely and effectively. There’s a chance that your layout is being messed up because naively replacing the domain name with a simple string replace, e.g. perl -pi -e ‘s/oldhost/newhost/g’ backup.sql, will not take into account things like serialized data. Try this on your … Read more