this has been asked numerous times... try
suspension FAQ look toward the bottom...
whether they will last...it really depends on how you drive, the drop, the kind of springs/coilovers(in your case you have better chances of them blowing cause they're coilovers and they tend to have a higher spring rate), and LUCK. also the ride is pretty badd with coilovers so getting shocks now would help with install costs(cause you'll most likely need them later on) and ride quality.