I purchased a Vantage Vue with console, and this note is to clarify my experience.
1 - No PC software is necessary. The station sends data to the console via some sort of radio link, and the console sends data to weatherlink via wifi. Wifi is necessary to talk to weatherlink, but not a PC. I think there is PC software that allows saving data on the hard drive, but I am not using my PC with the station.
2 - See #1.
3 - Does embed code on a web page work with the Basic (free) plan on weatherlink.com?
Yes, the embed displays current conditions when subscribed to the basic plan.
4 - The embed code updates the web page about once per minute. The browser user does not have to hit refresh.
5 - There are four embed display options, and there is some Davis branding (not much). There is nothing compact, so if you really want to control the display, see #6.
6 - Is a Pro/Pro+ plan required to use the software API (for current conditions)?
No, basic plan is ok for current conditions. I am now using the API to grab a few data points (temp, humidity, etc.). My guess is that the station uploads to the console periodically, and then the API hits the console, but this is good enough for backyard enthusiasts. The API documentation is good enough to get started with the JSON response, but then the programmer has to find the desired items in the large chunk of data. There is a VantagePro.Interop NuGet package for .NET, but I have not yet installed this. The last version is from 2014, maybe there is something on GitHub. The tedious part would be to write a class so that the JSON can be easily deserialized. A pure XML response is apparently not available.
Thanks, all!