1. The first coin somebody else mentioned Valentinian while I was thinking Valens. If you could make out the lettering around the edge that would probably clinch it. I can't make out anything on the reverse.
2. Can't tell anything on the second coin but after it was pointed out it does look like some non-roman script.
3. If your coins are impregnated with olive oil they probably won't react well to the H2o2. Not that the crud isn't there, just that the oil and water and non-mixing and all.
4. Where did you acquire these coins. If in a far-off distant land that might help with coin #2.
5. Agree with jwharper's valuations.
-wheatiefan