Yes, they can, but they need provide mailing address in Hong Kong, cannot provide China providence address. (cannot PO Box also)
No special restriction, use their POC passport is enough, cannot use their travel visa.
China people usually dont like China bank or HSBC, because they dont wont their money can check by the Chinese Government, also HSBC also check this and that on big amount money deposit in.........because HSBC dont want particpate on money laundary.
Citic Ka Wah is the China people like the most.........