I've gone ahead and installed an old version of Dreamweaver, CS6, and then I downloaded and installed the CS6 version of eCart that I just upgraded.
Now things feel like a lot more like I'm used to, however, eCart simply isn't functioning the way it should. For example, I'm trying to setup a new shipping calculator script, so I created a new PHP page, and then I go to Server Behaviors -> eCart -> Shipping -> US Postal Service.
When I click that, though, nothing happens. I mean the drop down I'm in goes away as if it saw the click, but no shipping wizard or anything pops up like it should so that I can enter all my shipping info and actually create this calculator.