I would think Congress certainly has the authority to require the U.S. Attorney General to be an attorney. In fact, the language used when the position was established under the Judiciary Act seems to state clearly that the position must be held by an attorney who has the credentials "to prosecute and conduct all suits in the Supreme Court in which the United States shall be concerned, etc."
I'd love to see President Trump prove that by taking it to the Supreme Court rather than meekly requesting a waiver under a law that is clearly not Constitutional.
Is James Mattis such an asset with no equals in that position that you'd even want someone to waste time and money in a court battle like this? LOL.
yes he makes liberals cringe and cry
Certainly. It's an important separation of powers issue. And there would be very little waste of time or money, given the slam-dunk nature of the issue in favor of the President.
As for AG requirements: all laws passed by Congress are subject to Constitutional scrutiny.
This, any and all of these "traditional" requirements you might specify are completely covered under the Senate's confirmation powers.
To be clear, the President has plenary power to nominate his cabinet members. Look up the definition of "plenary". That means that the President could nominate Ted Nugent to be AG if he wanted, and it would be up to the Senate to confirm the rock-n-roller or not.
In the history of this Republic, I'm not aware of any Constitutional limitation on the President's power to nominate the person of his choice for cabinet positions. The President nominates, and the Senate confirms (or not). It's that simple.