yep, the drive pins are the same as what is used on the traxxas 2wd xl-5 or vxl models. any hobby shop should have some in stock.

upgrading a servo can give you quicker/stronger steering.
the stock servos have plastic gears, which can strip. you can upgrade to servos with metal gears.
but on the shockwave there is really no point in doing so unless the stock servos fail/break.