Need PHP programmer. Need software similar to Digg.com

This site will be PHP/MySQL based. We want to start a site where the functionality will be similar to that of digg.com. It will have a registration system which captures the users name, e-mail, ability to create their own username & password. This site will be community oriented. Where users can submit rants/comments about various subjects (rant about a company they don't like, or comment about a sports broadcaster, bad experience at a restaraunt, etc) instead of submitting news. Only registered users will be allowed to submit the rants (as we call it). It won't automatically be posted on the main page, it'll have to be approved by one of the admins and then would be posted to the front page (with the amount of positive + votes next to the title. Option for us to determine how much of the rant will be posted (say 200 characters) before a read more link). There will be categories (technology, sports, music, movies, etc). We should have the ability to create all the different categories. We would also like a point system where a user can give the submitted rant/comment a positive or negative rating. Also an easy way to mass e-mail everyone who has signed up (sort of like a newsletter) would be nice too. We should be able to install this script (easy bundled instructions) or at least test it (for bugs & such), and after we're satisfied the money will be paid in full.