If you only need just a compressor clutch, why replace the whole compressor? Replacing just a clutch does not involve all the other operations you listed nor the concerns brought on by exposing the system to atmosphere!
But to answer your questions:
If you take your vehicle to a good mechanic that has the proper AC equipment, they can evacuate all the current freon out of your system instead of dumping it to atmosphere which is bad for the environment. An AC recovery machine will filter and store the freon for future reuse!
As to the Pag oil; a good AC mechanic will know how to put the oil into the system when charging.
If you install all a new compressor and all those other parts listed, you can drive it to a good AC mechanic shop as the system will be discharged and the low pressure switch will not allow the compressor clutch to energize...

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Supporting Vendor and Moderator of LOST05 Jeep Liberty CRD Limited 
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