Yes. The Nigerian visa is relatively expensive. The visa cost alone is $160. I recommend using a service to get the visa. My brother used Online Integrated Solutions (https://oisservices.com/visas-det.php?id=MTU=). It seems they have the lowest service fee. The downside is you have to go in person to give biometrics. I used Travel Visa Pro (https://www.travelvisapro.com/) to get my visa. You don't have to go in person, but their fees are very high. If you're not able to get the visa through a service, a visa on arrival is an option. It's technically only for business travelers, but there may be a way around this. The disadvantage of the visa on arrival is the cost (around $200 service charge) and dealing with the immigration folks to get the visa when you arrive.
Yes. They will check for this at the airport when you arrive in Lagos
We've agreed on a max capacity with Sheraton Hotel already, so the ceremony & reception will be strictly-by-invite.
in Nigeria, it's common to do both on the same day, particularly if you have guests coming from all over the place. We'll have the white wedding outside in the morning at the back of the Sheraton hotel. There is a lovely lawn perfect for a ceremony. Then we'll all relax a bit and change into our traditional clothes. The traditional wedding will then kick off in the banquet hall early afternoon. After the traditional wedding, we'll eat, dance and have fun.