Would the FIB continue warrantless spying on citizens even if Congress passes a law banning the practice?
Yes. Of course! It has been proven that the DOJ will not prosecute the illegal activities in which the feebles are already engaged. Another law won't make any difference.
What will make a difference is to cut funding to zero, fire every damned one of them, and bulldoze the building.
Absolutely. They lied to the FISA Court. They lied to Congress. They lied to the American people. Why would anyone believe they would follow any law?
So much for “99% of them are honest agents”.
“Would the FIB continue warrantless spying on citizens even if Congress passes a law banning the practice?”
They’d probably just transfer the warrantless spying back to the NSA like it was before Congress passed the law.