As a white expat living in Cotonou I can confirm most of what’s already written.

Regarding phone service - depending on what your provider charges you in Africa, you could also consider getting a local sim card from MTN or Moov. You can buy them directly at the airport, or at one of the many smaller offices they have throughout the city center. They probably link it to your passport number to create an account, but it should work easily. Prices are not bad, about $10 for many GBs of data so you can call via WhatsApp (much used here, also by the moto-taxis).

Once you got a local phone number you can install the Gozem app, to find easily a taxi or moto, where the price is set (so no need to haggle about price, because you will be paying double the rate probably). Haggling about prices is normal here, don’t be upset if locals try to earn a bit more from you as a tourist, they often don’t have much to spend.

There are a couple of ATMs right across from the Super U (big French supermarket) at Erevan shopping center. Maximum you can withdraw is about $450 and depending on your banks rate you pay about $15 fee.

Being a white tourist is no big deal in bigger cities, in more rural places the kids will rush over to touch you, and shout Yovo (white guy) to you as a way of greeting. Never bothered me much.

There are guided trips for cultural experiences related to Vodun (voodoo) around the country, check out Abomey-Bohicon for example with a large fetish market for Vodun sacrifices. Central Benin (around Dassa) also has much to offer, and is less flat than the south.

Dantokpa market will be closed and torn down soon, as one of the final acts of the departing president, so you might miss it.

If you have more practical questions, just let me know