Regarding the item marked "S. Ames", are you sure that last letter is an "s"? Could it be an "r", reading "Amer"?

If it could read "S. Amer", that may be for "Southern America" rather than a person's name. That was a very early war way of designating the CSA. I have seen that stamped on some guns imported from Europe (in particular those guns sold by a retailer in New Orleans). Note that the 18th Ga Inf was an early war organized unit, having been organized during the Spring of 1861.