Can i go and comeback to US before Visa Expiry


I am confused with the many people responces for the below question.

Currently I am in US and my Visa period is Jan14th 2013 to Jan 14th 2014. I am planning to visit india from Dec 8th to 24th 2013.

1.So is it fine to enter US at that time without having the extention applied?

2.If i already applied extention and still by that time it is not approved is it fine?

  1. or can i come back and apply for the extention?

Please answer me for the above three questions. It will be very helpful to me to travel my plan to attend for marriage.