Prepositions always confuse me

Question 1 

I am the winner of the speaking contest

I am the winner for the speaking contest

Which is right? and Why?

it seems that the difference between of and for  is not clear.

Question 2

why "in" the plane while we say on the bus and on the train

Thanks in advance

why "in" the plane while we say on the bus and on the train

Thanks in advance

Actually, it's correct to say "on the plane" and not "in the plane"

"Hurry, we have to get on the plane, it's almost ready to leave!"

This is true for talking about passengers, but also other things. "The cargo was loaded on the plane" but you can say "The cargo was loaded into (or in) the plane" and still mean the same thing. 

Thanks for all your help