organic chemistry - Rate of EAS in chlorobenzene and fluorobenzene

In both chlorobenzene and fluorobenzene, both the halogens show a −I effect where fluorine has more electron withdrawing effect than chlorine.

Now, if we consider the mesomeric/resonance effect, both show +M/+R effect. On comparison of resonance effect and inductive effect, resonance effect dominates over inductive effect. Then:

1. Why does −I effect dominates over +M/+R effect of chloro and fluoro group in the case of chlorobenzene and fluorobenzene? Give reason.

I know that the −I effect dominates over the +M/+R effect of the chlorine and fluorine substituents in case of chlorobenzene and fluorobenzene. Now, on the basis of this chlorobenzene should be more reactive for electrophilic aromatic substitution reaction than fluorobenzene (as −I effect: $\ce{-F~ >~ -Cl}$). But, it is not true though vice-versa is true.

2. Why is fluorobenzene more reactive for electrophilic aromatic substitution reaction than chlorobenzene? Give reason.