With respect to your question about measuring Flow Rate and Pressure, when applying a force to the Hydraulic Cylinder, I have edited one of our DEMO models to demonstrate that it is possible.
As in hydraulics, whether the driving force is the change in pressure or the force to the piston, the hydraulic cylinder will move, similarly in SimHydraulics models, it does not matter whether the hydraulic circuit is driven by 'change of pressure' or 'force to the piston'.
I have used the following example from the Documentation :
Double-Acting Hydraulic Cylinder with Flexible Clamping
I edited the model (attached), and have removed the pressure sources. Also in the 'sh_cylinder_da_flexible_clamping_Edited/ForceSensor' subsystem have an Ideal force input (set to 400 N). The force sensor output has been commented. With this Ideal force as the only source of input, you will notice the change in flow rates across the two parts of the cylinder.
Hence, as mentioned above, it is possible to have drive the cylinder using a mechanical force and measure the flow rates/ pressure across the cylinders.