Purchased an 1820 LD Large Cent - Newcomb-13 today!

I just purchased an 1820 Large Date, Coronet Large Cent from my brother-in-law for $100. He, somehow, purchased this at an auction for $7.50. I did some research and have determined it is Newcomb #13, because it has the die crack that encircles the obverse. I don't know anything about large cents. My questions are:

1) What do you think it would grade?
2) Should I send it to a TPG to get it slabbed?
3) Which TPG do you guys recommend?
4) Did I do ok spending $100?
5) Are there any known doubled dies for these? The L & Y in LIBERTY looks doubled.

Thanks folks, I need all the help I can get on something this old! Any other advise would be greatly appreciated.