The number of specific Twitter users per country or nationality is unknown.
125
nigerians
the rich nigerians do, but not all of them.
there are more than 50 thousand
Nigerians do gymnastics at gymnastic centers.
Nigerians like to dance to reggae songs.
there are good Nigerians, bad Nigerians, - just like there are good and bad Irish, French, English, Russians, Americans etc
About 18 million
Nigerians live in houses just like other people
Yes, Nigerians need a visa on arrival to Bangladesh
The stats for this would not exist, because there are many illegal immigrants from Nigeria in Johannesburg.
They don't have Twitter.