Great to see your progress.
To try and answer your questions:
Kangaroo is primarily a form-finding tool, but it can also be used for analysis with real values of material stiffness, load and deformation, for certain types of structures.
When form-finding there is no need to use real values for gravity or stiffness. Just like Otto, Gaudi and Isler making models with hanging chains and inverting to find compressive forms, or dipping wires in soap to shape tensile membranes, it is not a direct simulation of the building materials, but a process which makes use of key physical behaviours of the model material to generate a geometry with particular properties that will be useful for the later actual built structure
(the chain does not resist bending, so hangs in a shape of pure tension, the soap film stretches into a shape with equal tension in all directions).
The actual magnitude of the tensile forces in the chain or soap are not important for this step.
(though if you want to be really accurate, you do need to pay some attention to how you set up the relative weight and stiffness distribution in the form-finding simulation)
For analysis you can set real material stiffness values and get numerically meaningful deformations for things like cables, space frames with only axial forces, and bending rods in Kangaroo. See here for another thread on this. There is also a Grasshopper plugin by Cecilie called K2Engineering which uses Kangaroo and adds components to make setting up these simulations with real units and materials easier, with more tools for pre-stress and analysis.
For more detailed analysis of things like plates, shells and beams in Grasshopper, I’d recommend looking at Karamba. For volumetric analysis of solid parts I’d recommend Scan-and-Solve
For capturing animations using the slider and the Step Solver, one thing to be aware of is that for the ‘Animate’ input parameter, the actual value isn’t important - it only matters if it is zero or not. It is just a way of making use of the built in slider animate function of Grasshopper (which automatically updates a slider in increments and captures a frame for each). As long as the slider starts from zero, it begins by resetting the simulation, then each time the slider updates(to any positive value) it triggers a Kangaroo update (which means as many internal iterations as you have set in the ‘SubIterations’ input).
The way I generally use it is to move the slider around manually to see how many iterations it takes to reach the point in the simulation I want the animation to stop at, then right click the slider and choose animate, setting the frame count to this number of iterations divided by my SubIterations setting.
Finally, about the interaction speed in Mac. I do want to fix this, but I’m afraid I don’t know enough yet about what causes the issue to know how long this might take.