Universal physical laws would qualify as all-powerful

They're prohibited from doing a whole lot of things.

I presume that's what Einstein thought

Einstein has confused so many people by his various statements about religion that we'd better leave him out. In fact everybody, no matter where they fall on the atheist-religious spectrum, goes around saying Einstein would've agreed with them. As if that mattered.

Is goodness required for the existence of God, or is it just an asserted property?

Opinions differ. But I'd guess the overwhelming majority of believers (yep even Deists) consider God to be mind-like, not equation-like, so argument from common use doesn't favor you.