harry potter - How Did Tom Riddle Find Out About the Existence/Location of the Chamber of Secrets?

Corvinus Gaunt himself know the actual entrance to the Chamber of Secrets and has been a student of Hogwarts.

But instead of opening the Chamber he decided to hide it in the girls toilet at the time toilets were established at Hogwarts. The theory that the basilisk was actually an anti muggle defense is in fact great but has a little problem, only a wizard could see the castle.

But I think Salazar Slytherin was actually using old roman water technology of aqueduct when he created the Chamber of Secrets. So I think the Chamber was originally located under a fountain and Corvinus changed this.

Living about the time of 1700 Corvinus Gaunt had a clear problem to create the modification he need a clear excuse. And what better excuse could be if he said that he has been told about a monster in Hogwarts , but knows about a secret Chamber. So he could use the entrance in the girls bathroom actually as an excuse to lock the creature in her secret Chamber. Thats how he could know about the entrance and create the legend but could not open the Chamber.

But the second Parselmouth after Salazar Slytherin was eventually forgotten and no other Gaunt ever attended Hogwarts. Then Tom Marvolo Riddle probably found during his school time a text from Corvinus.Tom Riddle still needed six years to find the Chamber.

The rest is no problem telling the basilisk to close its eyes and bring it under Tom's Imperius Curse.

The case with Ginny Weasley is a simple one too. Under Trance by the Horcrux, the Horcrux simply uses Ginny's body but ordered the Basilisk as a living Tom would do.

Harry's cases is more complicated. At first there are the two Horcrux the Diary and Harry, but the Riddle Horcrux acted like the living Riddle allowing Harry to enter. What Voldemort would not know is that probably all the defense spells which stop others from entering the Chamber were actually bound with the Basilisk.So he lowered them for Harry to enter, but Harry simply destroyed the spells that shield the Chamber by killing the Basilisk. If the Basilisk was dead anyone could enter who speak parselmouth even without knowledge of what it sounds like.

Dumbledore could have tried to have Morfin Gaunt released from Azkaban. Maybe Morfin not only shows Dumbledore his past but also writes for him texts to understand parselmouth in order to help Dumbledore defeating Voldemort. That's
why Dumbledore knows what Morfin says, but probably refused to use it by himself