The Goonies find a coin in the wishing well with the portrait of Kennedy on it, making it a Kennedy Half-Dollar. Who throws half-dollar coins into wishing wells?
Rich snobs with money to burn. AKA, the usual fare of the local Country Club.
Why does One-Eyed Willie have an eye patch? Based on the fact that there's bone underneath, he didn't lose the eye, he was born without it.
Because he wanted people to look at him and instantly realize that he's a force to be reckoned with. There's no better way to do that than to have an Eyepatch of Power.
In the Novelization, Mikey conjectures that Willy wore the eyepatch in order to disguise a birth defect as a battle scar.
Spielberg has openly admitted that the most iconic scene in Raiders of the Lost Ark was taken from Carl Barks' Uncle Scrooge comics — has he or anyone else involved ever admitted the same about the entire premise/plot of this film?
So every treasure hunt adventure is a ripoff of Uncle Scrooge? Robert Louis Stevenson, you time-traveling con artist!
Considering that she apparently speaks no English, how did Rosalita understand enough of what was going on to tell them to stop signing the papers? She doesn't even have any particular reason to care about those people losing their houses, does she?
Two possibilities: despite not caring particularly for Mikey and his family, she had still been hired to work for them and so was showing loyalty to the ones paying her; or far more likely, a lack of knowledge of English wouldn't stop her from understanding how sleazy and smarmy Perkins was, or that he was ruining things for all the kids' innocent families (who had not done anything to her, after all). Not to mention her background would make her far more likely to sympathize with several close-knit, lower-middle class families than a bunch of snobbish rich people who would treat her as bad as or worse than the Goonies and their families.
Re: the papers, it's apparently common knowledge what's happening to the Goondocks. Mikey's mother says "I want the house to be clean when they tear it down" so Rosalita obviously knows what's going on. As to why she cares, maybe she's just a decent human being?