Nice finds!
I can offer no thoughts on the nickel. The dollar, though, does not look like it has been all that badly compromised by possible exposure to fire.
Before resorting to electrolysis or other more "heavy artillery" cleanong methods, I would try soaking the dollar overnight in highly diluted household vinegar. Use common white vinegar from the grocery store, and cut it with water to a 20-25% solution. If the treatment sows progress, it can be repeated. You may never get the coin perfectly clean, though.
artorius