Source: UESP Wiki page: "Skyrim:Elder Knowledge"
Get beat up by some vampires
no they actually get harder
Yes and No. The game is based on a level system. There is said to be an unlimited number of quests. If you get to around level 81-82, you stop leveling up. If by beat, you mean finish the main story line then yes. If by finishing the game beyond playability, then no.
beat the game twice then look back at the menu and there it is.
A month and a half but someone could beat it sooner
the elder is in the biggest house.
No, you do not need the Sunder and the Keening artifacts to beat "The Elder Scrolls III: Morrowind." While they are essential for certain quests and provide unique gameplay experiences, the main storyline can be completed without them. However, acquiring these artifacts can enhance your character's abilities and offer additional narrative depth.
you get it from the Celestic Town elder after you beat Cyrus
You can keep playing if that's what you're asking unlike in Fallout 3.
you get it from the sprout tower elder after you beat him
you have to beat the elder at violet city
Beat the companion's quest line, ask him to be your follower, lead him out of the city, kill him.