Okay!
first things first!
I am a Ghanaian and i've lived in different parts of Africa and I would like to clarify a few things.
I'm sorry if this appears a little pretentious but yam is one of my favourite foods and I also hate people having misconceptions about my country and my continent. its like someone thinking every American is white or all pizza is on a thin crust.
There are many different kinds of yams in every part of Africa. Bayare is the word for yam in twi, which is a ghanaian language and its not the name of a specific yam.
Some of the names of yams that I know are puna, punjo & water yam, among others. I don't know very many though. Cassava is NOT a kind of yam. It is a tuber just like yam but it is not yam.
Secondly, kenkey is NOT made from yam. It is made from maize/corn (they're the same thing. just different words, maize being the british word, i believe).
pd, what you had was fried yam, which is the equivalent of french fries and which i love. Just like you describe, they are crunchy on the outside and almost fluffy on the inside.
now yam refers to the food.
'nyam' means 'to eat' in parts of west africa. in eastern africa, nyama is meat in swahili. it is often grilled and eaten in large gatherings. that's the only explanation I can think of for yam being used for a gathering. but then my swahili is limited.
Yam can be cooked in a variety of ways: boiled, mashed, fried and depending on the kind you have, it tastes better.
Puna, for example, is excellent which ever way it is cooked, but water yam isn't very good boiled or fried but it good mashed. it is best eaten with a sauce though for those of us who love yams, when you find a good yam, you can eat it cooked without a sauce.
In ghana, boiled yam is often eaten with garden eggs/eggplant stew or spinach stew. garden eggs are a type of eggplant which I am yet to find in the states. they are of a cream colour and taste quite different.
when fried, they are often eaten with shito( spicy fish sauce) and/or with a fresh salsa-like sauce made with fresh chillis, onions, fresh tomatoes.
when mashed, they are often eaten with soup and the mashed yam is cooked in a specific way.
I think that's all i've got to say but please feel free to ask if you have any questions.