[gaotongfei]

"Is it easy to handle salary payments to China " - yes, through Paypal

"will the Chinese Firewall interfere with any web development activity they have to do" - Most of the Chinese programmers know how to bypass the firewall by using VPN or shadowsocks.

Rails developer here, I have been following remote job listing sites for a really long time. Its frustrating when most of them set limitation as for "US"/"EU"/"NA" citizens only.