CMS & WordPress
How do I edit and view offline so to speak any changes I have made to page templates, before I make them live?
I usually set up a local copy of the site on my computer, including the database on localhost, and set the right paths in the configuration to get it working properly. Normally I have deployment scripts, SCM and so on as well. But minimally, I'd say you can set up a web server on your localhost and download WordPress to there, then do your changes and see them on http://localhost/yoursite.com or whatever you call the folder.
Thanks, was thinking this was the case - i've never done this before, does it take long to do and learn.
If you run Windows I would suggest installing WAMP.
There are a bunch of maintenance plugins you could use to achieve this, i usually like to skip doing things offline and work straight online, i prefer this plugin:
WordPress › ThemeFuse Maintenance Mode « WordPress Plugins