Hello feiko.lai,
For some steps that support fine-level distribution, the memory consumption in network mode would be lower, when it's not require to keep all the data in memory.
As for the GPU node, in the version 1.3, you can set the "Capability" for the nodes: CPU, GPU or Any. If you set GPU capability to the node, it will mean that the node would be used only for GPU-supported tasks (image matching and depth maps calculation), while other tasks should be performed on other nodes.