Again, please read the official announcement I linked to …
This does not matter.
SketchUp 2016 and earlier versions (on MS Windows OS) use a MS Internet Explorer browser frame for it’s internal web feature interfaces.
SketchUp 2017 and later versions (both platforms) use an internal Chromium browser frame for it’s internal web feature interfaces.
No, I do not think so. 3DW is no longer supported from inside SketchUp 2016 and earlier because it uses Internet Explorer browser frame.
Externally (from SketchUp,) you can use Chrome, Safari, Firefox or MS Edge to browse the 3D Warehouse and download models to a folder.