There are a lot of people currently expressing new forms of activism, social media is playing a huge part these days.
Most definitely! Social media is one of the biggest ways people get there information right now.
Yes, it's a great way to start what's referred to as 'grassroots' campaigns.
I have heard many references to such, but I am not that familiar with the term. Please tell me more about it. 
Grassroots refers to creating campaigns from the 'bottom-up', rather than from the top-down and are considered as being more natural.