Redesign of Existing Website

HI All, I am currently having a website which is all about cloud computing. It has various features like blog , articles, tutorial, freelance etc ( few more would be added soon). All of these features are placed in different sub domains and are currently working as individual components. The issue is all of them are created with direct open source implementation. For example , blog in my site is a word press implementation, while articles implementation is a media wiki installation. and each of them have their own login system and database. Now I want to get the total website redesigned and development with new look and feel and enriched User interface and high quality look and feel. I require a single logon for all the applications may it be freelance , article or expertzone etc. Also i want the feeds of all features to be shown on homepage. Also user should be able to login using their Google Plus, Facebook , twitter accounts. The company which will take up the job needs to deploy the entire application on my site. I require this to be done within 20 days. so request only experienced companies to bid for these. no single developer or freelancers please. Regards, Naveen.G