its java. Symbian is s60 and above.
U cant download symbian software, but there are many java versions of apps and games to download, try sites like phoneky, getjar, and mobango for java software to download free.
No. C3-00 uses Nokia proprietary OS and it does not allow you to install 3rd party applications like Symbian, which is an open source OS. You are only limited to use some JAVA based applications.