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

Section 207K(2A)-(3), Electoral Act 1993, (amended 2023):
207K Overseas donation or contribution may not exceed $50
(2A) If a party secretary receives from an overseas person a donation that either on
its own or when aggregated with all other donations made by or on behalf of
the same overseas person during the same year ending 31 December exceeds $50, the party secretary must, within 20 working days of receipt of the donation,—
(a) return to the overseas person the total amount donated by the overseas
person, or its value, less $50; or
(b) if this is not possible, pay the total amount donated by the overseas per‐
son, or its value, less $50 to the Electoral Commission.
(3) If a candidate or party secretary receives, from a donor who is not an overseas
person (as defined in subsection (1)), a donation funded from contributions that
includes any contribution exceeding $50 made by or on behalf of an overseas person or any contributions made by or on behalf of the same overseas person that when aggregated exceed $50, the candidate or party secretary must, within 20 working days after notification of that fact under section 207C,—
(a) give back to the donor the amount of the donation, or its value; or
(b) if this is not possible, pay the amount of the donation, or its value, to the
Electoral Commission.
 

There is no ban, but there is a NZD 50 limit on such donations.