H-4 visa application

Hi all,
I'm going to apply for my H-4 visa in shanghai. On the D-156 form, it says "how long are you intend to stay in USA" and "The purpose of your trip".
For the first question: should I reply until the end of my H-4 approval notice date. For the second one, should I say visit or stay with my hu*****and?

It's almost 5 years I haven't go back home. I'm a little nervous and worry about my visa to get back.

Thank you for your help!!!