Carbonyl compounds undergo electrophilic additon reactions

Carbonyl compounds mainly show nucleophilic addition. reactions. Why?

Haloalkanes undergo nucleophilic substitution reactions while haloarenes undergo electrophilic substitution reactions. Explian.

Why do aldehydes and ketones undergo nucleophilic addition reaction?

Why does benzene undergo electrophilic substitution reaction easily and nucleophilic substitution with difficulty ?

Why alkynes undergo nucleophilic addition reaction while simple alkenes do not ?

Assertion: Aniline does not undergo Friedel Crafts reaction. Reason : Friedel Crafts reaction 1s an electrophilic substitution reaction.

Explain S_N^2 reactions. What is the preference order of different alkyl halides to undergo nucleophilic substitution reaction via SN2 mechanism ?