It just might be some surface junk that might come off with the use of a soft cloth.

Second, the set sells on eBay for around $20 a set so if you do damage the coins you can buy another set for a reasonable price.

Nice find on the swizzle sticks....not worth a lot of money ($1 - $2 per stick) but they are nice stick to own. The brown/red/yellow variegation is a harder stick to find that the solid color sticks.