Upvote:15
The first coin doesn't have much detail to go by. But the second coin looks like it might have two soldiers standing with banners. Some Roman coins have that. Here's an example of a coin with Constantine I, c 334-335:
There are a couple of pages with coin cleaning tips on the web. In short: toothpicks, toothbrushes, soap, and (distilled) water; gently, with a lot of care and patience.