I'm moving back to Google Zurich. The male/female ratio is a huge issue there, so it's good to bring a girlfriend, but cost of living was never a problem. Taxes are minimal, salary at Google Zurich is huge.
My colleague worked in Zurich for 6 years, he didn't even try Google because he was already making comparable money in other company, so I would call salary in Zurich as "huge", just average for Zurich.
Yes, but Switzerland is a special case in general. Even post-docs (research assistants) at academic institutions have near six-figure salaries (CHF 85K, in quite theoretic field). A lot of non-hype tech companies provide six-figure salaries for engineers. I can't imagine any non-junior engineer to relocate to Zurich for anything below that.
Glassdoor doesn't look at the tax differences (use a tax calculator), the fact that Google gives you 8.5% pension that you can use either to buy a flat (I have done it from my Swiss pension money), create a company or use it in emergency, and also you can take it out (after paying taxes) if you leave the country. Also I don't believe the 200k pound figure for Facebook London as a median compensation package. Can somebody confirm it?