How to hide for development?

I have a site being hosted by a third party; I had a ‘coming soon’ page which was just a index.html page and when I entered the URL, it displayed correctly.

The host just installed WP for me and now when I type in the URL, I cannot see the ‘coming soon’ page… it goes directly to WP. It seems the index.html file was deleted during the WP installation; I was able to put the index.html back on the site and it works but, now, I cannot get to WP in order to work on it so I renamed it to xindex.html.

Now my questions:

1) How can I show the index.html (coming soon page) AND be able to hide the developmental WP work as we figure out how to install themes, and customize and add content?

2) Finally, once we are satisfied, how do we drop the index.html (coming soon) page and make the shiny new WP site visible to the public when they enter the URL?

Thanks in advance for any help.