Are the sliders and tracks lubricated, if they are, are the back of the pads (where the touch the caliper) lubricated, lack of lubrication can cause the pad to stick against the rotor and cause a squeal. Also, were the and tits on the back of the pads, I've seen it before where there is a tit or nub that is used for holding a shim on that is in a wrong spot where it will push the pad against the rotor and cause it stay applied even with the brakes off. Also, are there shims on the pads, I've seen it before where the pads are just slightly thicker then factory specs and the shim can take up that amount of extra space and keep the pad against the rotor. Did you change rotors, and if so, was the style where you had to change bearings over. If so, did you over tighten the bearing.
as for the squealing it could be related, or it could be caused by cheap pads (I see this all the tie), it could be caused by new pads and old rotors, or a squealer tab that is bent and nearly touching. There are many variables for both situations, they may be related, or the might also be separate issues, but go after the stiff wheel first, that will lead to bigger problems then a noise, start there and work your way to the noise.
Also, the other caliper should be changed, breaks should always be done by the axle, not by the corner. are are the calipers for the right application?