i used to have nade in 'f' in coh1 but it seems to be different keys in coh2. for example PG nade is 'e' witch is quite good if you use wsad for movement, q for attack move, r for reinforce, t for retreat,f for upgrading flamer etc.
for building selection i use default F1 for HQ, F2 for T1 etc. for unit production i use mouse
Statistically they are balanced out to have no advantage at close or long range. Other factors like abilities or squad plans likely skew this to some degree.
i.e. molotovs are close range weapons whereas rifle-grenades are long range.