MAYA _ replace skinned mesh

To replace a skinned mesh by another : SKin -> Substitute geometry
very useful to replace with a High Res Mesh or when a mesh is messed up (uv,normals) it also keeps the deformer but not the blendshapes.  source A   source B

MAYA _ Ik spring solver

Ik spring solver is useful on  multiple joint chain for proportional or custom rotation of the joints with the ik. Just enter this mel command to be able to create them : ikSpringSolver;

MAYA _ parent object to particle

select particle shape node and a transform node, then in connection editor :