I used to use WL exclusively but when they dropped the screw top vials (yes it was a while ago) and enough of my yeast squirted out of the top of those soft plastic bags when I snipped the top off, I made the transition to Fermentis and never looked back. When our local HBS here in San Antonio...
With an induction cook top, the element is on or off and heat control is amazing. Also, there is little to no heat retention in the ceramic top so moving the pot off the element to avoid additional/residual heat is totally unnecessary.
A pillow case will work just fine. It will take a bit of extra time for the wort to drain so I would suggest a way to suspend the heavy wort and grain filled bag until it drains as much as possible.
A brewmaster told me some time ago to set my gap to the width of a credit card at the numbers on the card. Since then I have always hit my "numbers" with that setting on a cheap 2 roller mill.
It would be very quick and easy to disassemble the union for cleaning. The crimp rings would not move and provide very little in the way of a space to hide any yuck. The nuts and the "union" could be rinsed completely.
The union is still the least expensive and best way to salvage the chiller.