7 tasks for a social networking site

Project Description:
We have an exciting & growing social networking site and would like your help in bringing our website to the next level with more sophisticated features.

Must be proficient in PHP, MySQL, Ajax, joomla, & jQuery.

Must have worked on social networking site previously & can show which sites these were.

It is relatively simple if you have the coding already, it is just that there is quite a bit to do. We have a budget of $350 and need to achieve all that can be done for $350 in the order as follows asap. Let me know what you can do for $350 - please note - winning bid will not necessarily be able to do everything on list.

Features include:

1a) Auto update (long polling with jQuery)
We want it to be Facebook alike, which time (eg. John commented 10 minutes ago), feed updates, and notifications, would show automatically by itself without refreshing the site.

1b) Infinite scroll JavaScript modification
Reference:
http://masonry.desandro.com/demos/infinite-scroll.html

1c) 3 rows display JavaScript modification on layout resolution (wordpress to jomsocial )
http://masonry.desandro.com/demos/images.html

2) Auto html link retrieving (video, snapshots of website, jpg) in status
We want our site to auto retrieve a "website address" whenever users copy and paste it on the status area, and then "auto transform" a thumbnails and description like facebook.

3) Email instantiate failure (cannot send email)
Our website is not able to send emails to users according to their activities in the site, such as new user registrations, new private messages, new friend requests, etc. We need to send emails to users upon these circumstances. We also need a backend admin page to select which activities do notify users and which do not.

4) Facebook alike “Share” function to share other users photos or links

5) Security for source code
Security for source code means encode username and password with some special process and encrypted source code with API, so the whole site is encrptyed in API packages

6)User privacy settings
Our site cannot limit specific friends (e.g. boss) to view the content of our profile. We want a panel to deal with that. Privacy setting should cover the disclosure of photos and videos, status, and friends of friends shared etc.

7) url rewriting
Our website had a minor function to let user know the exact website address of where they are browsing (it is not useful for most people, but can be a threat to us if we exposed it to "hackers"/technical guys.
Reference:
http://coding.smashingmagazine.com/2011/11/02/introduction-to-url-rewriting/

All features must be extremely secure.