Wow! Great work!

Maybe the capsule can slightly rotate in anticipation of a turn (assuming the capsule is cylindrical in shape). In that case, you won't be pulled to the side during cornering much like banked turn of an aircraft.

As soon as I saw Concorde, a railgun and an air hockey table, I thought of Ekranoplans. http://en.wikipedia.org/wiki/Ekranoplan

So Elon Musk throws some vague ideas out to fuel interest about a futuristic transport system.
Serious engineers and scientists around the world gather to solve the puzzle of the mysterious machine. The think tank comes up with a few viable solutions to the problem.
Elon Musk appears before the audience, takes the results and picks one to satisfy everyone's desire for an answer. :b

http://vixra.org/pdf/1301.0043v1.pdf This is the actual Hyper-loop that Elon has put his own physics in to improve efficiency.

Wheels in the tube would cause drag unless they are supposed to magically pop out when needed. High pressure coming in from the side will not create a smooth airflow going forward. The concorde is made for high speed so it could be that a concorde nosed capsule will push air out of the way and magnets will propel it or the magnets will levitate it and wind will push it forward?
Why not just go with a vacuum?

Northrop-grummman had a concept for a ground based ekronoplane with a launch mechanism. called TTWIG-TRACK TETHERED WING IN GROUND EFFECT- ANOTHER WAY OUT IMPOSSIBL CONCEPT.

My guess is something similar to a maglev train, except that it rides on an air cushion instead of a magnetic field.
This would eliminate the very high cost per mile for maglev track, as the air cushion track could just be plain old concrete with an electrified rail for power.
The issues would be the noise and vibration generated by the air cushion, plus all of the usual right-of-way problems faced by trains.

Having perforated walls would allow air flow to bypass a capsule in the event that one stopped ahead of the other. This scenario could allow a crash. Unless you had a significant amount of check valves....

Elon's largest obstacle will not be the physics behind this idea—it will the politics (this coming from experience). He will meet resistance from politically entrenched contractors demanding they be part of the action or else they will stifle his efforts.