What is Disk 2 for?
It has been a long time since I installed the game. But from what I can read here, http://sims4.crinrict.com/en/2014/09/installing-from-dvd/ it's needed to install the game.
Is it required?
I think so
What's in it?
The files to install the rest of the game, or maybe the extra content, I'm really not sure.
Can she still use Disk 1 and 2?
She can use them, but won't be able to install.
Can she still use the code even though it's been used?
No, the code is connected to your account and that where it will be connected to.
And can she download The Sims 4 for her own Origin profile?
No, not with your code, she needs to buy the game herself.
