Subject: effects of wind(air resistance), gravity, surfaces on speed

I am trying to find research data on the effects of the variables in our 
environment on speed.

Say, in the area of bicycling:
1.how much does the wind (depending on direction) have an impact on 
cycling speed?
2.how much do differing gradients of hills impact on speed?
3.how would the addition of another cyclist riding in a paceline affect 
speed? how about another 2 cyclists? or 3? or 4? etc.

Re: effects of wind(air resistance), gravity, surfaces on speed