All of the chassis are basically equal, only setup matters and the kit stock setup is usually pretty good. In your FIRST build get a reamer and drill bits to make sure all of the suspension components move absolutely free and then some, a tiny amount of binding can ruin an otherwise perfect car.
Boosting means having dynamic timing advance built into your ESC, giving the motor far more RPM capability than it could have with static timing.
Most ESC's on the market today are pretty good, but Tekin and LRP seem to have the 1/12 market curbed. If you get the LRP Stock Spec V2, Orion 1s, or Viper 1s, you can run 1 cell without a booster.
The biggest advantage you can get for 1/12 racing is an old-timer at your track who knows all of the tricks and you actually LISTEN.
The biggest mistake I made when I started off was I didn't realize that the wrong tires look like the right tires but certainly don't work like the right tires.