Here are a couple illustrations of an installed dryer. It may not be exactly like yours but it should be able to tell you where things go to.
The ones marked 1 and 2 are the pinched off lines. The other is the service connection. The last drawing is of a typical guage hookup for adding the freon.
Yes that is what you need to do. I have done automotive air conditioners but never refrigerators so i am not sure if there are any precautions that must be taken aside from a thourough evac before charging the system.
No you dont need two driers The prifonal drier needs to be taken out.