Hello @ghparadise,
Welcome to the Plugin Café forum and the Cinema 4D development community, it is great to have you with us!
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About your First Questions
It depends a bit on what you meant with 'the documentation of Python Redshift'.
Classic API
The old redshift module Python API never has been official and was therefore integrated into the Python documentation. This old redshift module targeted the GraphView, i.e., Xpresso node material of Redshift. Technically you did not need that API, as you could retrieve the 'node' branch of a Redshift material, and the rest is then more lest just standard c4d.modules.graphview code. Except for us helping users from time to time here on the forum, there are no SDK code examples for this API.
Nodes API
But your screenshot concerns a node material for the Node Editor, i.e., the 'new' node system. There is no dedicated API for Redshift (required) here, and instead you just use the general purpose Nodes API.
The technical documentation can be found
here. The Nodes API encompasses the graph, nodes, and nodespace frameworks.
Here you can find our Nodes API Python examples, including material nodes and Redshift examples.
Where can I find the document of these string parameter just like "com.redshift3d.redshift4c4d.nodes.core.texturesampler".
You cannot, the Redshift attributes are currently not exposed both in the C++ and Python API. What you can do however, is use the Node Editor. Press CTRL + E to open the preferences, and activate the option IDs under Node Editor.
4bd6db15-8efc-4a60-bb79-2529de10efba-image.png
When you now select a node, you see its Asset ID (the ID used to instantiate the node) and its ID (the ID used to reference this specific node in the graph):
178ce2f0-967a-4697-b629-9efb0e7fd3a0-image.png
When you select a port, you will also see its ID.
399bb9d2-7e7a-4dcb-8288-1bebb3f58a5d-image.png
Where can I find the document of these method just like "FindChild","AddChild","GetInputs" and so on.
They are part of the Nodes API. These function names are a bit ambiguous as the appear on multiple types. You are likely talking about GraphModelInterface, which is the interface representing a graph, and GraphNode which represents entities in a graph such as nodes and ports.
Cheers,
Ferdinand