If that’s obsidian/volcanic glass- and it looks like it- it is very easy and pleasant material to knap. You can drive super long flakes with little effort. Obsidian is even used by a few flintknappers to make specialized surgery scalpels today.
Absolutely... But these are dated to over 9k ago and prismatic and very obviously struck in the hammer and anvil technique. You don’t find this later even in the 1,300s except for in the mesoamerican cultures. Even in North America they were still not this advanced until later. These are very advanced lithics for this timeline.
Old news... John Snow used this stuff to kill a snow king and his skinny troops...