Dell India — Dell Vostro 3590 Laptop; 1 year old; Issues of Screen Freeze, Sudden Screen Blanks, Frequent Hangs,and Battery Life

I bought my Dell Vostro 3590 laptop almost 1.2 years back. For the last 2.5 months, my laptop is facing several issues. They are:
1) Screen suddenly freezes at least twice a day and I have to power off the laptop and again start it
2) While doing slightly heavy surfing, the laptop gets hanged many times
3) The battery life of my laptop is almost 15-20 mins after only 1.2 years o[censored]sage

Please guide and help me regarding the issues, there's a lot of hindrances caused at work.

Thank you.