how to set up a joint

Hi everyone,
I just started learning the Motionview, so I have little experience. And I had a couple of questions.
My design is to have 4 buds on the floor. In the middle, a pump will be installed on top, which should rotate around the x-axis and the y-axis. There are 2 centers of mass in the system, which are connected by forces.
1) I'm interested in pump rotation, I couldn't set up the universal joint to allow rotation in R_x and R_y, so I added 2 revolute joints that should perform this function. Does this construction make sense?
a) if yes, how to set up damping so that the expression is close to reality, I don’t quite understand what specific values I need to insert into the settings
b)if not, how to solve this problem
2)how to set up 4 joints, which prevent the structure from falling under the floor so that in -z they receive force, but not in +z (so that the structure can rise, in case of a positive force on the joint (imitation of reality)).
3) DOF-Question, is it ok?
Thank you!
Best regards,
Anton