Passport is to be valid for one month minimally, from the dated of granted entry visa.
Valid visa and international vaccination card, with vaccination against yellow fever, are a must.
Visa duty exists. The visa could be granted at Benin Embassies in Germany, Belgium, France or in Russia.
Announce duty is not extra specified. Nevertheless, we recommend you to check at Benin Embassy, before your trip, whether some conditions for travelling would not changed in the meantime.
Information and warnings on travelling abroad is to be found HERE.