AF-S does not mean that it is only for DX. If it is DX, then the lens is built for DX bodies.
50mm 1.8G, 70-300 are all FX compatible. If you have 35mm 1.8G AF-S DX, then it might not work well on a FX body.
But I fail to understand one thing, how does moving to FX solve the lens changing...