What would be the likely repercussions of flying into the Air Force One temporary flight restriction area?
The answer to each of the points in your question is "Maybe".
A pilot wandering into a presidential TFR (and many other "VIP Movement" TFRs) potentially faces some pretty severe consequences. Quoting the standard language from one such TFR NOTAM:


  THE FEDERAL AVIATION ADMINISTRATION (FAA) CLASSIFIES THE AIRSPACE DEFINED IN THIS NOTAM AS 'NATIONAL DEFENSE AIRSPACE'. PILOTS WHO DO NOT ADHERE TO THE FOLLOWING PROCEDURES MAY BE INTERCEPTED, DETAINED AND INTERVIEWED BY LAW ENFORCEMENT / SECURITY PERSONNEL.
   ANY OF THE FOLLOWING ADDITIONAL ACTIONS MAY ALSO BE TAKEN AGAINST A PILOT WHO DOES NOT COMPLY WITH THE REQUIREMENTS OR ANY SPECIAL INSTRUCTIONS OR PROCEDURES ANNOUNCED IN THIS NOTAM:
  
  A) THE FAA MAY TAKE ADMINISTRATIVE ACTION, INCLUDING IMPOSING CIVIL PENALTIES AND THE SUSPENSION OR REVOCATION OF AIRMEN CERTIFICATES; OR  
  
  B) THE UNITED STATES GOVERNMENT MAY PURSUE CRIMINAL CHARGES, INCLUDING CHARGES UNDER TITLE 49 OF THE UNITED STATES CODE, SECTION 46307; OR  
  
  C) THE UNITED STATES GOVERNMENT MAY USE DEADLY FORCE AGAINST THE AIRBORNE AIRCRAFT, IF IT IS DETERMINED THAT THE AIRCRAFT POSES AN IMMINENT SECURITY THREAT.




That's a lot of MAYs, so what does it mean in practice?


The pilot will be detained and interviewed by law enforcement
May is a nice word, but in practice if a pilot flies into one of these TFRs they will be held and questioned once they're on the ground to find out why it happened. It's kind of a big deal.
The pilot will face some kind of Administrative Action from the FAA
Suspension or revocation of their certificate is certainly possible (especially if it's not the first time).
A stern talking-to from someone at the FSDO and/or a reexamination ("709 ride") is almost certain.
The pilot may face Civil Penalties (a nice way of saying "fines")
$10,000 used to be the magic number for these fines as defined in 49USC, the law now refers back to 18USC (which I'm not going to read through because reading the US Code makes my head hurt), but I assume it hasn't gone down. The point is it could be an expensive error.
The pilot may face Criminal Charges (arrest and imprisonment)
I can't recall a case of a pilot accidentally violating a TFR and being locked up for it, but I imagine willfully violating a TFR could land you in prison pretty easily.
Use of deadly force may occur (the pilot may be shot down)
Again, I can't recall a case where a pilot has violated a TFR and been blown out of the sky by a missile from an F-16 (though there are plenty of cases where aircraft have been intercepted and diverted), but it is an option available if the aircraft poses an "imminent security threat", however that determination is made.