I used to experience something similar with VPLIVE not finding the application file and trying to remember what I have done.
One thing I have found to work better for me using both Weatherlink and VPlive at the same time, I launch VPLive first before launching Weatherlink itself. In this way, VPlive does what it needs then opens up. Once VPlive is open THEN i open Weatherlink itself.
For instance, here is the order I run things.
1)I boot my PC.
2)I launch Virtual VP.
3)I launch VPLive and hold til it completely opens.
4)Once VPLive is up an running, I then launch Weatherlink.
With this order, they seem to function fine with one another. In my case I have an original Vantage Pro and run the Weatherlink 5.71 App.
I hope this helps with your error messages.
Sorry I can not help on your WU issue as I use Cumulus for that.
Good luck..