I need an explaination

Google + and its many uses.  Help?

Twitter:  I speak and promote but what benefit does it have?

FB page:  what are its benefits?

My author page is informative but I have noticed a difference between those that like my blogs and those who like/read my books.  How should I mesh these in together?

I see many an author do video’s.  What are the points to this?  Does it have to be that high tech?  I’m trying to get to the next gen without feeling like a dinosaur.  Input.  I see over 100 fans, I’d like more than just a few responses please.