Ask HN: User Generated Content with social signals as voting system?

This is what I want to do

a) users submit their own generated content on my website through a page with forms

b) content gets to me to be moderated

c) I approve the content and it goes live on a section of the website

d) users promote their content to their connections

e) content with the most likes/pins/tweets/+1s at the end of the period wins (ie an ipad)

PROBLEMS

1) facebook states you can't use likes as voting system. But this is for a competition on the website, not on the facebook page. Does it still apply ?

2) It seems there are apps that automate most of this, but these are for facebook. I'd like all the action to be on the website and social media as a sharing/voting platform

Does anybody have any experience in this?

Thank you