Help me understand how much power a US. president has here.

[COL Mustard]

1. I'm told there are some limits

But generally, yes, a President can declassify most things that originate from the Executive Departments. A President can also direct that someone receive a security clearance if he feels that it's necessary, even though the person is generally not otherwise qualified. Again, there are some limits and *MOST* Presidents (well, all except the last one) have abided by those rules.

Generally, as I understand it (and my security experience is dated) there is a document review and the agencies that developed/classified the documents are given input, and there's something in writing to support the declassification decision. There is no "declassification wand" that a President can just wave and say "Poof, you're no longer TS/SCI".

I am of course not surprised that TFG would break those norms as cavalierly as he apparently did.