Ive been having some problems with my brakes for a while now. First of all, i noticed that under high speed braking, everything shook. Also, under medium to light braking, there was a moaning sound. So i think to myself, no big deal, ill get new rotors. I got new rotors(drilled in front, oem in back), pads, and a new left rear caliper(It was in bad shape when i took it off). Problem seemed to be fixed, but before i got done breaking in the new stuff, i had slam on the breaks pretty hard(comin over a hill at around 60, and found mailman stopped in the middle of the road). Needless to say, my brakes were smoking. Now, whenever i brake the same moaning noise is back , and the shaking is back as well(not quite as bad as last time). What could have happend? Did the hard braking destroy my new rotors?

Also, im probly an idiot for doing this, but when i replaced the caliper, there was a circular weight looking thing attached to a bracket that was attached to the caliper. The new caliper didnt have the same bracket, nor the means to put the old one on it, so i left the weight thing off... could this be part of the problem?