Beginner Numismatics questions

I just started collecting, and I was hoping to get a little help here.

  1. I found a proof roos dime, is it worth anything beyond face value? I have no idea what condition it would be classified as, I’m just assuming that it was so damaged (taken out of a piggy bank after 5-10 years) that the proof condition wouldn’t affect it. It’s not silver.

  2. I purchased a few US mint proof coin sets in the original plastic case, and it seems like a few coins are damaged inside the packaging. Also, I see microscopic debris and oil on some of the coins. Am I better off leaving it in the case and the coins may decay more, or should I do an emergency rescue mission?

  3. What is a good numismatic community forum to join? I found one a while back that seemed really active, I hope I can find it again. One thing I remember was a “Let’s practice grading” thread where people posted pictures of their coins and the community members would try to grade it. Another thread I remember was “what is the strangest thing you have done with your coins.”

Thanks in advance.