Replacing the compressor is fairly easy. You need to loosen the multibelt before you can replace the compressor, but the activity itself is as straight forward as unbolting the old one (& removing the hoses) and putting in the new one (& connect the hoses).
As long as you do not leave the airco system (disconnected compressor hoses) open for a longer time period, you do not have to change the dryer. If you leave the airco hoses disconnected for a longer time period (a couple of hours), the dryer will get filled with moisture that is in the air and you will need to replace it.
with a minor 600+k