What exactly gets sealed?
AFM, valve cover, oil pan, header, cam angle sensor, fuel pressure regulator
Basically the stuff that can be adjusted in order to gain power.
Is use of the autolite sparkplugs mandatory for the class? Are they sealed into the car?
Not mandatory but there needs to be standardization in the test procedure and Kevin at MCE like to use the Autolites. You can change them at a future time for maintenance. The spark plugs are not 'sealed'. They can be removed and re-installed, replaced etc. Spark plug wires too but I think the electrical connectors to the coil packs are 'sealed'.
Do the seals get in the way of any maintenance?
No. Unless you need to smog the car by setting ignition timing back to stock
If a car produces more than the permitted power, how is it dialed back?
Not sure but probably mostly ignition timing and air fuel ratios. If your car/engine makes too much power on the dyno, then he won't be able to seal it and you'll have to run SMT (Regional class w/ Toyo RR) or SM (National class running Hohos).
In SFR, Sealed SM is for NA 1.6 cars. The 1.8 cars won't be able to hit the meager torque maximums defined in the rules based on the 1.6 RWHP and RWTQ capabilities or lack thereof... I mentioned that to the board once b/c I was confused and they pointed that out.
Hope that helps. Have you made it to a race out here yet?