iOS and MySQL : PHP or .NET Plugin ?

Hi everyone, I'm currently working on a multiplayer video game and I choose mySQL to store and retrieve persistent informations. This game have to run a several platforms (PC/Mac, WebPlayer -> Facebook, Android & iOS).

I wrote some PHP scripts to communicate with my database, but I don't know if I can use a Mysql Client plugin instead (http://www.codeproject.com/Articles/43438/Connect-C-to-MySQL). I think it will be better and faster, but I dont know if this plugin will works on a Android, iOS or WebPlayer build.

Anyone experiment this ?

Furthermore : currently I made static functions for MySQL SELECT, INSERT INTO and UPDATE, and I directly send the query with POST data. A remote PHP script execute the query, and send back serialized informations (JSon). It's better for me to have just 3 functions able to query what a want, when I want, but I wonder if this method can cause some security problems (because of the query directly send).

Thanks you for your help, and sorry for my french english...