My questions this time relates to a scenario in which I already have a "live" (commercially operational) Zen-Cart based web site, then I need to apply some changes/improvements to it.

So far, I managed to test most of Zen Cart's functionality locally (on an XAMPP based windows server).

But there is at least one feature that cannot be tested locally: PayPal payments.

Also, operations in which the real SSL certificate is involved cannot be tested either, as they require the real URL (vs. example.com).

As Zen Cart is a critical business tool, I am sure that I am not the first one dealing with this problem: I would like to be able to "flip the switch" from an existing (operational) web site to the new one (with either minor or major changes that I applied).

What is the proper way to do that?

Thanks,
Daniel

P.S. I don't have a commercially operational web site yet. I am just trying to plan ahead.