Processor Help

Hi, I am a student on a budget and am looking for a laptop. There are three different processors available though,

1. Pentium B950 ( 2.1 ghz)

2. 3rd gen i3 3110 (2.4 ghz)

3. 3rd gen i5 3210 (2.5 ghz)

I will be using my computer for web, music, HD video, streaming music and video, and word processing. So my questions are...

1. What processors power-wise would be good for me.

2. But most of all, will any of these processors affect battery life. ( I've heard that the pentium is more efficient.)

Any advice would be appreciated. :)