How can the following conversion be carried out?

Aniline to chlorobenzene

Explain the following:

Chlorine present in chlorobenzene is ortho and para directing

Explain the following:

Aryl halides are extremely less reactive towards nucleophilic substitution.

Explain the following:

Presence of a nitro group at ortho or para position increases the reactivity of haloarenes towards nucleophilic substitution.

Explain the following:

Aryl iodides can be prepared by reaction of arenes with iodine in presence of an oxidizing agent.