SImulation with hypoplastic model for granular materials in ABAQUS

Hello, I want to use the hypoplastic model for granular materials downloaded from https://soilmodels.com/download/plaxis-umat-hypoplas-zip. The UMAT file umat.for is the model for sand. I followed the instruction https://web.natur.cuni.cz/uhigug/masin/plaxumat/node5.html. I have some questions about the initial state variables and the model itself:
(1) The initial state variables should be assigned in the input file, but I found it can work if I did not. Are there any problems? I found the StVarIni.for, which includes a loop to assign the parameters 17-22 to the initial state variables 1-6? Does this file is necessary?
(2) I found the parameters of the model are seemed highly related to void ratios. I want to use in dynamic analysis, how can I calibrate the parameter hs (I think this one is related to shear modulus) by G0? And I found the pressure-dependency is considered by the parameter n. If I assign n=1, the model is pressure-independent? and the ground is homogeneous?
Any comments or suggestions are highly appreciated.