Disk Caliper wont go back on
It seems like the cotter pin had to go in at an angle like the nut wasnt going far enough. Checked the races of the bearings but they seem in there.
IMO
take it apart,
check to be sure the seals are correct and seated deep enough. If they are, then;clean out the grease , knock out the races and verify that what you put in, is the same as what you took out, and that the cones properly fit in the cups. While they are out you can verify that there is not something at the bottom of the bores that is preventing the bearing races from seating, especially the inner one;on account of that could cause both of your problems. In my experience with those brakes, there has always been ALMOST TOO MUCH room for the cotterpin.
If you didn't change the pads, then you should not have had to push the pistons back in, other than to clear the ridge at the outer diameters of the rotor. That should have been a clue.
Pushing all 4 pistons back in evenly can be a chore.
If the master cylinder was full before you started, that returning fluid has not got much place to go, except up into the cap.
"seem in there", is not good enough. If they move later, while your motoring down the hiway ........ God only knows what could happen, and it won't be anything good.