1. Is there a ban on donations from foreign interests to political parties?

Paragraph 441e: (a) It shall be unlawful for— (1) a foreign national, directly or indirectly, to make— (A) a contribution or donation of money or other thing of value, or to make an express or implied promise to make a contribution or donation, in connection with a Federal, State, or local election; (B) a contribution or donation to a committee of a political party; or (C) an expenditure, independent expenditure, or disbursement for an electioneering communication (within the meaning of section 304(f)(3)) (2 U.S.C. § 434(f)(3)).

United States Code, Title 2, The Congress.