Dear @Kajal.Thakur,
Regarding (1), yes. The documentation mentions that the gravitational term is not included in the stated hydrostatic matrix because it often intrinsically accounted for in structural solvers (as it is in OpenFAST).
Regarding (2), the equation I state applies to both the roll (4,4) and pitch (5,5) terms. The full-system mass and vertical center of mass of the NREL 5-MW baseline wind turbine atop the OC4-DeepCwind semisubmersible is available in my post dated Feb 13, 2020 in the following forum topic: OC4-DeepCwind semisubmersible - WAMIT Files.
Best regards,