I'm confused. Maybe I didn't explain it right.

I'm just trying to understand how SSL and HTTPS works.

Hypothetically, say I have an existing website, and I want to install SSL to reassure visitors, but are apprehensive about possible incompatibilities that may then be exposed and need fixing.

Right now, in FF there are no 'in your face warnings' unless there's a page with a form.

If I have SSL installed on the server but no Redirect to HTTPS set up yet does the website appear as before? (Does the HTTPS prefix force the page to use the SSL?)

In other words I can access a page via http://www.myDomain.com - and it appears as before
And, can I also access that same page via https://www.myDomain.com - which may then more visually warn of insecure items? (this way I could see and fix some problems before forcing HTTPS redirect)

Would that work?