3. Is there a ban on corporate donations to political parties?

Article 19, Decree-law of 2011-87, 2011, of the organization of political parties:
political parties are prohibited from accepting: - direct or indirect financing, in cash or in kind, issued by any foreign entity.

Article 75, organic-law 2014-16, 2014, 26th May, of the elections and referendums: the electoral campaign and the referendum campaign shall be financed solely with self-financing and private financing in accordance with what is regulated by this law.

Unofficial English translation.

Political parties are prohibited to accept help, gifts and donations from people and public or private legal entities, with the exception of financing allocated to the state budget.