How can I export 3d model from unity3d file? and any other type of assets?
In a pinch, you could extract the geometry, textures and shaders with 3D ripper DX (haven't tested this).
there is not any built in feature for what you want. you can access mesh data and write them to the format that you love. for textures it's easier because there is a function for encoding the data to PNG format. the EncodeToPng gives you an array that you should write to a file yourself. there is a script inside the unify community wiki that exports models to obj format. the script is not much complete and don't export animations or skins&bones and ... the script is called ObjExporter. there is another one called TerrainObjExporter for exporting your terrain.
You can not. You can access models you have already imported into Unity3d by locating the Asset folder in your project.
Please elaborate your question if I did not get it :)
I need some way to use vertices's structure of 3d model, which inside of unity3d package.
is there are any possible methods to do this?