Great stuff!
A couple of comments:
First, muffin tins make good ingot moulds, especially when you can get them cheap (Goodwill, garage sales, etc.). I suspect that waiting for the ingots to harden is one thing that slows you down. They're not real strong so they need to be on something sturdy enough to keep them from bending. A dozen or so of these and you're making a LOT of ingots in a hurry.
Second, to avoid any issues with moisture on the wheel weights being added to the pot, and speed up melting, you could set up a 'preheat' bucket on a small burner - something like an old charcoal or gas grill. Don't have to melt in that bucket, but get it hot enough to drive off any water and also reduce the melt time.
Good article and pictures!