Urgent help required

During the previous year, assessee was carrying out a sole proprietorship business for april 2013 to december 2013. He converted his proprietory business to a private limited company from january 2014.

i have following queries :

1. whether AMT will be applicable or MAT will be applicable ?

2. what are the provisions required to be checked while conducting tax audits ?

3. whether 2 returns will required to furnish or 1 ?

4. which form to be filled ITR4 or ITR6 ?

5. what other compliances are required to be checked ?

please help me in other matters which are required to be checked or take care while performing audit ?

thank you