Regarding the copper... is the owner allowed to sell the copper on the open Market, or at a discount? Or is resale not allowed?
This is actually built into the system. Not only is the owner allowed to sell copper, they are assumed to be doing so. Revenue from copper sales will be added to the mine's income along with a percentage of revenue from copper alloys. Similar rules will apply for other metals should their mines go up for auction. If a second copper mine becomes available, sales revenues will be split between them.
However, note that nothing will be earned the same night property is bought. So if you buy the copper mine currently being auctioned, it will not generate sales or income for you until Night 2.