QTR-Quadtone RIP

This is a basic question that I'm unclear about.  I have used the Forum Search feature and not come up with a clear answer.

1) If you have the PK (or MK) ink set for 75 and the default blank, does that mean the PK prints at 75% of the maximum amount of ink the printer will release?

2) If you have the PK (or MK) ink set for 75 and the Default Ink Limit at say 50, what is the amount of ink the printer lays down?

3) If you have the PK (or MK) ink set for 75 and a Second ink at 35 with the Default Ink Limit Blank, what is the total max density the printer produces?  Is it 75 + 40 = 115?

4) If you have the PK (or MK) ink set for 75 and a second ink at 40 with the Default Ink Limit at 90, what is the total max density the printer produces? 

Thanks, Terry