Issue one：Is a web based retail store, operated by a Person in US, hosted on a computer in China, available only in Chinese language, selling to both US and Chinese customers, subject to the U.S. laws?
Answer: if the store is selling to US customers, it is definitely subject to to US laws. The standard here is the minimum contact test, as explained in https://en.wikipedia.org/wiki/Minimum_contacts
If the customers are all from China, I doubt it is subject to US laws.
Issue two: Is a web based retail store a "public accomodation" as defined in US civil right act?
Answer: I don't think retail store are even covered under Civil Right Act, except those contains restaurants. https://www.law.cornell.edu/uscode/text/42/2000a
As for American Disability Act, there is a case ruling that holds a web based store is NOT a public accomodation as defined in American Disability Act. see https://www.morganlewis.com/pubs/ninth-circuit-holds-that-ada-is-applicable-only-to-actual-physical-place
