Sometimes it takes the VM a minute to load the desktop. Sometimes you have to close it and reopen it for first time use. 

Yes. There is even a Horizon App you can download. 

We are working on the problem but for now: 

  • Close the browser (don't log out of the virtual desktop) 
  • Restart the browser
  • Connect to the virtual desktop 
  • Your mouse pointer should now be visible 

The USB pass through does not work in a browser.  You will have to install the Horizon client and then it will work.  We are looking into the problem