How hard is it to learn French?
It depends. If you are gifted and if you love this language, yes. Honestly, French is much more difficult than English.
Is it easy to make friends in France?
It's difficult to answer since it depends on your person, yourself. Some Chinese may get friends everywhere, while some French can not even get friends in France. If you can make friends in US, there is no reason that you can't make griends in france, or in Uk, or in other place.
As for Chinese food market, you can find easily in Paris.
The high tax aims at the peole who ean more than one millions euros per year.