Hogwarts seems to think "recent history" is everything from the last three hundred years or so, including the Salem witch trials, which didn't kill any witches but did make a lot of them nervous. The most notable event of the period was Grindelwald's War, which was very similar to the World War 2 Cam remembers except that Hitler was being mind-controlled by wizards the whole time. It's notable both as a major war and as the closest wizards have come to losing their secrecy; reading between the lines it looks like there was some brinkmanship with both wizarding sides trying to influence the outcome of the muggle war without being blatantly obvious about it. Albus Dumbledore, yes that one, was already an adult at the time and a major player, first on the "stealthily helping Churchill" side and then killing Grindelwald in a duel shortly before the fall of Berlin, enabling same. There's also some more recent material featuring Voldemort (who many of the books refuse to name even once) and Harry Potter (about whom many of the books speculate wildly).
There are lots of kinds of magical snakes, including one with three heads, one that spontaneously generates in fires, and one that moves by biting its own tail and rolling like a hula hoop.
Alchemy is an extremely complicated and just plain weird discipline; it resembles a cross between chemistry, a pun competition, and a four-year-old's imagination games. Ingredients are sometimes treated as substances, sometimes as metaphors for concepts, and sometimes as interchangeable with their names; one of the simpler recipes involves cooking down pears until they turn into peas and harvesting the extra "r"s for a later step. The philosopher's stone is speculated about, both as an object and as a symbol of moral and intellectual perfection. A couple of the books mention Nicholas and Perenelle Flamel as the six-hundred-year-old creators of a real one, but they never explained how they did it.