Whith shader language does ue3 support ?

Whith shader language does ue3 support ? And Can i use “&” operate in cgsl?

That depends on renderer, dx gonna use hlsl, opengl gonna use glsl, the material editor generates code to specific one, exception is custom shader block which will include code to shader at its raw form, so you would need to make material for each renderer.

I am not sure if you mean UE4 but I will assume that you do. UE4 does use HLSL under the hood but that does not mean that you can just throw HLSL shader commands at the shader network and get things to work. Under the hood UE4 does a lot of optimization, called folding, to help reduce the cost of the shader at hand. When you use the custom node in your shader UE4 will omit all of this folding and that could make your shader run very slow on your target device. I would first try and see if what you are trying to achieve can me done via the nodes that are already in the engine and then if you still can not get the results you are looking for then you should use the custom node.