Warm vinegar will generally soften the most stubborn old glue on old furniture. Dipping the parts to be reglued in warm water, and then letting them dry out completely, will help to open up the wood pores and allow the new glue to enter the wood more freely. Warming the parts on top of a heater or in the sun will also help open up the pores of the old wood before regluing.
Just about everyone knows to apply light penetrating oil or silicone spray to the hinges. But to really rid your door of squeaks, use your hammer and pry bar to lift the hinge pins up an inch or so. Apply the oil or spray to the top of the hinge, then wait a minute or two before you tap the pin back in place.