First off, welcome to the site!
Okay, now for your problem, have you checked the caliper slides to make sure they are greased and not seized? This can cause uneven wear on the pads and the side with the issue to wear when the others don't. What happens is the caliper needs to move freely on the slides to bring the outer pad in contact with the rotor, as the piston presses the inner pad in. From the way you explain it this seems to be your problem.
As for the spongyness, could be air in the lines, but if you don't have a leak, or haven't done any work, there should be no reason for this.
You could also have a bad passenger side caliper. It's possible this could be the cause of it not releasing and vibrating. Did you drive it after you released the caliper? If so, how did it act then?
With the amount of wear you have on you brakes your fluid level should be low. As the pads wear down the piston needs to be out further and requires more fluid in the lines, in return appearing as low brake fluid.
Have you checked your fuses for the defrost? If fuses are okay, check for a broken wire connection going to the element in the back window.
BTW, try a little better on your grammar, it was a little hard to read.
Hope this helps, report back if you find out something more, have any more questions, or if you solve the problem.
Good luck
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