new spheres should sort out the movement probem as long as the rear arm suspension bearings have not seized, the brake problem is very common as the rear brakes take there pressure from rear suspension they only work at there maximum when carrying full loads this is to prevent rear wheel lock under light loads with the caliper being alloy and the pads being steel backed they tend to seize into place, remove the pads clean out all the rust and debris and apply some copper ease to the back and edges of the pads making sure non gets on the friction material, this should sort out the brake problem another common problem is rust between the caliper body and the suspension arm resulting in the caliper twisting causing binding and in severe cases the caliper catching the inside of the wheel to sort this the caliper will have to be removed and all corrosion cleaned out an copper ease applied between the caliper and the suspension arm hope this helps
bob k
March 2010