2. Is there a ban on donations from foreign interests to candidates?

Section 3(1) & 2 Foreign Interference Act 1982

D3. (1) Subject  to  the  provisions  of  this  Act,  it  shall  not  be lawful for an alien to perform, do, hold, take part in, aid or abet, or allow, any restricted activity in Malta.
(2) For the purposes of this Act, "a restricted activity" means - (a) any  activity,  or  participation  in  any  activity,  of  a political  nature  or  having  a  political  purpose  at  any time during the period commencing nine months prior to the date on which Parliament would, unless sooner dissolved, stand dissolved by virtue of article 76(2) of the Constitution and the date of the publication of the results  of  an  election,  or  at  any  time  between  the dissolution of Parliament according to article 76(1) of the Constitution and the date of the publication of the results of an election;
(b)  the  provision  at  any  time  to  or  for  the  benefit  of  a political  party,  person,  club  or  similar  institution, whether directly or through an intermediary agent, of any money, equipment or other material, by way of gift or  otherwise  not  against  equivalent  valuable consideration, excluding books and other publications intended  for  sale  or  distribution  not  exclusively  or mainly for Malta, unless such provision is authorised by the Monitoring Committee in accordance with this Act.

There is a ban on foreign donation, but exceptions could be made.