Presidents and Top Secret clearance.

Here’s a previous thread (pre Trump) that deals with pretty much the same question. Short answer is that yes, the President has access to all classified info, since the power to classify is derived from Executive orders issued by the President:

I’d say it’s a safe assumption that would extend to his advisors as well - if he says “Advisor X should have access to all top secret information”, no one has the power to say no to that.

As regards your second question - the Constitution spells out the requirements to be President - 35 years old, natural citizen, 14 years resident in the USA. An attempt to add further requirements by the legislature (Congress or state) would likely result in a challenge/constitutional crisis.