Cool find I'm not a currency specialist, but my guess is in that condition with the writing, it would be unlikely there would be a premium or at least anything that would make it worth the time and expense to sell on ebay. However, I would definitely keep it if I found it
The bill would probably sell for $25-35 on eBay. You can get the writing and ink stamp off of that note with acetone. Same as coins; don't scrub it, just let it soak.
Not in the best of shape but that is a nice find and should have a small premium due to the overall condition.
I would say unfortunately no, condition is the number one factor in buying notes in general, if the condition was better I would say a minor premium to the right person but the writing on front is a real distraction, and would make it undesirable to most.
That is an excess ink smear, but with the teller's stamp and writing, it would have a very small premium, I would think. For $5, I'd just keep it with my currency collection.