Chromecast Audio with PC Spotify client

[Neil_UK]

I am trialling Premium for 3 months at the moment, hoping to be able to switch the family to a family premium account. My son has a smartphone, no problems. I have a linux desktop, several linux laptops, an android tablet and a chromebook. I am IT literate, and can overcome IT hassles. My wife has a windows 10 laptop using chrome browser, and is not IT literate, will spit feathers at the slightest IT problem. Neither of us oldies will be getting a smartphone any time soon.

I want to be able to set up the various HiFis each with a streamer target for Spotify Connect, ideally something like Chromecast Audio. I do not want to dedicate any of the linux boxes to this duty, as I want to avoid logging in/out to share the HiFi. 

I understand that there are issues controlling the Chromecast from a PC client, and there is a workaround using an android device as an intermediate.

Questions

??? It's not clear whether this workaround is done one time, to populate the cast-to list, or has to be done each time a connection is to be established. Once done, can the tablet be removed, or does it need to stay active ???

??? Does the fact that my wife uses a chrome browser mean that a chromecast could be cast to from a tab in the browser, perhaps if spotify was running in the web interface, rather than the PC client???

??? Are there other inexpensive web streamer targets that do not have this problem, and can use spotify connect directly from the PC client ???