Sagging on one side?

For the squeak, I would lie on the ground and pull the bumper down or push up until you can reproduce the sound. Look and listen for the sound. I would suggest lubing all joints/rods. Probably will need another person to help diag the noise if the grease job doesn't solve it.

For the sag, make sure a rear left leaf spring is not broken. Look at the front upper and lower arms for anything that looks different. Maybe your squeak and sag are related.
Make sure your tires are at the proper pressure. Look at your torsion bar adjustment bolts. These can be adjusted to raise or lower the front end.