It’s hard to suggest w/o knowing the needs for the staging/dev site. As it sounds like you need to have the content copied in a place you can fiddle with settings/accounts, the import approach does sound best. Keep in mind the media will reference the production site, which is probably ok.
The WP Beginner article is more or less a manual approach to doing what the Installatron Cloner does. You can still run into problems with their approach because it’s more than just a search and replace on URLs; many theme options store things in arrays that are “serialized” in Wordpress. You can run into problems if the length of URLs differs between production and staging (using a dev.domain.org is a good idea as it will map okay to www.domain.org)
That’s why the Installatron Cloner is so awesome, it accounts for this difference too.
My preference for development and testing (following the lead of Rom Woodward) is to run Varying Vagrant Vagrants on my laptop. I run several test domains where you can do everything in WP you do on a server. This is most useful for doing design and plugin development, but it totally rocks. I can even do testing when I am offline (e.g. in a plane).
Nice to hear of one of our earliest DS106 students doing serious web stuff now! Hi Lee