Facebook,Twitter integration and Uploading files to Rails app

We have a rails app as same as Michael Hartl's Ruby on Rails Tutorial book; -A user can authenticate the app and sharing posts with their followers.(like Twitter) We have just added some features to our app and now we want add the basic features; --- Twitter, Facebook integration --- 1) Sign up with Twitter and Facebook with omniauth 2) Sharing the posts with Facebook and Twitter Note: We have already Facebook and Twitter developer accounts. We have created an app both of them. --- Uploading files to posts (photo and video) 3) Adding multipl files such as photos and videos to posts (video conversion to . mp4 with using ffmpeg or something like that is important for watching the videos with all devices. Sometimes it take more time and we want to proceeding these feature in the background If the [login to view URL] is big. We can also discuss the alternatives with freelancer ) 4) Show the posts which are created with horizontally scrolling 5) Upload the profile photo for user (We have already use gravatar for users. But, when users haven't got gravatar or they want to change their photo they can upload a photo with cropping it) Note: We have already used Carrierwave for uploading files but we can discuss it if you want to change it to Paperclip or sth.