As of changing background color (icon) this is possible but can’t say for sure what configuration option does it. Maybe node type and/or icon path. This part of documentation might help (until someone who knows this stuff jumps in):
A very useful way to understand the coloring and what it means is to create a component and go into edit mode. At the bottom is a drop down that allows you to change the component type and it shows the list of Types and Colors…
node_type: the type of the node, one of:
knext.NodeType.MANIPULATOR: a node that manipulates data.
knext.NodeType.LEARNER: a node learning a model that is typically consumed by a PREDICTOR.
knext.NodeType.PREDICTOR: a node that predicts something typically using a model provided by a LEARNER.
knext.NodeType.SOURCE: a node producing data.
knext.NodeType.SINK: a node consuming data.
knext.NodeType.VISUALIZER: a node that visualizes data.
knext.NodeType.OTHER: a node that doesn’t fit any of the other node types.