Here I am with 9 * to go, with my own thoughts and questions,thinking there has been nothing posted here in ages so everyone else must have done it by now.
What you get depends on what you have or haven't already claimed.
However on finishing all nodes with 3 * on a floor, there are the extra boosts and bonuses which vary from floor to floor, I think if you actually read it, it explains it exactly in the text in Hellheim.
It might not have been possible to copy and paste the information here, and would have taken too long to type it all out , then I had an idea....
Below is the forum link to the official explanation from the admin staff.