Internal audit

Hi friends

I have a doubt regarding the internal audit department in a Limited company.

01.Whether internal audit head should compulsorily hold a qualification ?

02.If yes , wats the basic qualification ?

03.If internal audit head can be a company staff ?

04.If the person does not hold any qualification but with the experience in a same company can be a internal audit head ?

Pls clarrify my doubts and so thankful to all the friends in advance.