Answer by Christo Thomas Jose:
Yes, it is necessary to mention the source, or it will make your content duplicate if you are copying it blindly to your blog or website.
It depends upon the niche you are handling. If its something related to technology, you can check out Mashable(), TechCrunch( ) etc. If its related to Mac or Apple products, check out Cult of Mac. If its related to social media, check out SEOMOZ(now ) or Social Media Examiner.
There is no limit whatsoever for posting anything from Facebook or Twitter, as your customers might be living in different time zones.
You can use the same content to post to different social networks with the help ofor with .