Yes, the deformation workflow in Kit is still under development and subject to change, hence the wrap deformer and other deformers are not exposed so much to user yet.
Skinning computation is currently handled differently in different stack than wrap deformer. But in the future we are working on bringing skinning, blendshapes, and other deformers into the same stack that user can author.
Re: modularity of your asset.
Kit is USD native, so by default you can take advantage of USD Layer composition for combining different elements of the character. Kit has a Layer widget extension (not exposed in Machinima) that allows you to author certain aspect of USD layers. Try it out. Machinima however is targeting a simpler workflow for wider audience, so certain more technical tools are usually not enabled by default. If you don’t see the extension available in Extension window in Machinima, you might find it in Create.
Re: Attach Animation and Attach Animation Force.
These two functionality are now available in the Sequencer and Property window.
But to answer your question. You can use these by first selecting the skeleton prim and the skelAnimation prim, then run the tool.
Attach Animation: This sets the relationship of your skeleton prim animation source to point to the skelAnimation.
Attach Animation Force : Same like Attach Animation, but also sets the joints attribute in the skelAnimation to match the joints in the skeleton prim. This was once used when the animation exported from other DCC has baked in namespace in the name. But I think our dcc connector like in Maya already have a way to strip out the namespace.
If you are into python scripting, Toolbox are all written in Python.
In the image below:
#1 You can click the folder icon, and it will bring you to where the python codes are.
#2 Shows that you can have your own scripts added to the menu. The instruction is as shown in the Extension ReadMe