Oh dear, such a lot of questions there.
The water management system (large plastic thing on left hand side) has a water softener unit, this is what look murky, through which your water goes through before entering the machine. The softened water leaves this part and enters your machine. The machine will then go through a pre wash rinse, empty, fill again and do a main wash. It then does a cold rinse followed by an extremely hot rinse. The water will again be discharged and the machine waits for a pre-determined period while the crockery dries using residual heat. The heater is not used to dry the crockery. This is why plastic doesn't dry, it doesn't retain heat very well.
Finally it will flush the water softener unit with salt water and pump the contents out. This is why you should still put salt in the reservoir of your dishwasher, 3,4 or 5 in tablets which contain "salt" cannot flush out the water softener. You can't overdose the machine with salt as the salt never gets to the crockery.
As to the groaning noise, when you had the base off did you notice if the wash pump was a large black unit or a silver one? If it's the large black one (Askoll pump) this will be the cause. High failure rate with them.