It may very well be band material (If it's flakes) otherwise it is normal.
The pressure of the fluid hitting the oposing blades in the converter will wear the aluminum off also cause a black film in the bottom of the pan. (which is normal)
x2 on the coasting in after shut off.
You just flooded that bushing when you ran the car, and theres no way it's going to run dry that fast.
Towing any distance at all would be disastrous though.
I wouldn't tow a TF more more than a few miles with the driveline in.
Good point on the screen filter SG, I had forgotten about those, but he said it only whines when rolling. (couldn't hurt though)