Good you sorted it out yourself while i was away. Yes, QuickCure3 works quite differently to Cure3 firmware and doesn't require the many additional steps using the device's native firmware. Much simplier and always worth trying first particularly if you're not very used to that sort of thing.

The vehicle SRF files need to be replaced in the "Vehicle" folder, you can do that manually if you have a backup of the file system or just connect it to WebUpdater or GarminExpress. You mentioned using the latter, so hook up the zumo to GE and go to "Tools & Content" the under the tab name Utilities scroll down to Optional Updates > Other Updates and select what you want. You can also update Language Files in Optional Updates as well.

Did you add a basemap as well from the link I gave you? If not the device will work but will crash when scrolling the detail map zoomed out when it tries to hand over to the basemap.