Looking for someone to develop a multi-platform mobile application for a project we run.

The application should work the same on:
Windows Phone 7
Android (2.x.x - Smartphones)
iPhone (including iPhoneOS 5.0 notifications)
Blackberry

and should provide extra functionality for users of:
iPad
Android (3.x.x - Tablets)

The application for the smartphones consists of those modules:

1. The systems consits of a list of possible "categories". The list of categories should be downloaded from a JSON serialzed WebService I'll provide. This list length is unlimited, and should be selectable from a menu.
2. A page containing a feed for the chosen category. the feed can be either taken from an RSS export of my application or a JSON export. the developer can choose which one he prefers.
The design of each feed-item will be provided to the freelancer who'll get the job.
3. The application should support multi-lingual interfaces, and should give me, the owner, an easy way to add languages. Most important is the support to non LTR languages (e.g. Arabic, Hebrew..)
4. The application needs to authenticate the user by his FB account.
5. There should be a search screen, which will get it's data from a search WebService (either RSS or JSON) I'll provide.
6. There should be a reading screen which will display the chosen Feed-Item with extra information it'll gather from a JSON WebService I'll provide.
7. The feed is dynamic and should update itself every 30~60 seconds.
8. There should also be background service providing notifications, if the user choose to get those. Those notification are the updates to the feed (every 30~60 seconds). The feed could be also the search itself. The user can request as notifications per category.
9. The developer will provide all source codes and projects, including all extras (graphics raw etc..) to us (Doron Ben-David/Senamtic Ltd.).
10. The application should provide us with the option to change it's design easily enough. Meaning, no need to write code in order to change the template.
11. It should take no time to load a page base. The only time should be the AJAX calls to the WebServices. While loading data, a "Loading" message should appear.
12. Moving between page should be by using gestures. Moving between categories by moving hand right/left. moving hand to the left when viewing an item should pop back the feed list. When the first category is shown, moving the hand to the left will pop the category selection screen. When the last category is shown, moving the hand to the right will pop the search screen.
13. The user should be able to manage his user's profile from within the application - This means he can choose what categories he want to see, and also filter the feed-items with given rules. Note that those filtering are being done by the WebService, when the application provides the Cookie of the user. The developer of the app should authenticate the user (again, via Facebook) with our Webservices first, in order to get a token.
14. When viewing a feed-item, the user can comment on that news item, or publish it to his FB (we provide the WebService for that). We'll provide webservices for commenting also.
15. We'll perform at least two code & design reviews during the process.

For the tablet/iPad application:

Everything is the same, except the display of the feed Items (both list and single feed). A design skeleton will be provided by us.
Also, the list of categories should be displayed not as a menu, but as a full page with extra informaion for each category.

When bidding, please take into consideration that although we do not limit the platform being used, we prefer NOT TO USE PhoneGap for the implementations mainly due to performance problems. Although, if you'll prove us wrong, we'll accept it also.
When bidding, please let me know if you are planning to use PhoneGap instead of Objective C, JAVA with ADT and Silverlight for WP7. We ofcourse willing to pay more for you not to use PhoneGap