Harry defeats Voldemort and Harry decides not to keep the Elder Wand.
Seamus survived the final battle but nothing else is known about his later life.
Hogwarts survived the battle in Deathly Hallows, and remains standing 19 years later when Harry's children attend the school.
Yes it is set nineteen years later.
No.
Harry gets the elder wand, destroys it. Then it moves to a cut scene 19 years later.
With an epilogue (19 years later).
It depends what you're talking about. If you mean the last chapter of Deathly Hallows (not including the epilogue) the chapter name is "The Flaw in the Plan." But if not, the epilogue is just called nineteen years later. of if you are talking of the book its Deathly Hallows, movie (last) Deathly Hallows part 2
Typically, memories are stored in Dumbledore's pensieve (when not in their original owner's heads). But specifically in Deathly Hallows, Snape's memories are stored (temporarily) in a vial that Hermione conjured. They are later dumped into the aforementioned pensieve.
I believe those details have not been revealed yet.
Ron goes with Harry to go and find Horcruxes. And then he leaves, but eventually comes back and saves Harry's life and destroys a Horcrux. Then later he helps the Order in the Battle at Hogwarts
There is no chapter where he gets married it just goes to 19 years later and he is already married
The wand was buried in Albus Dumbledore's palms when Dumbledore was buried. It was later found by Lord Voldemort