1) The lines and every system component must be flushed so that the lubricant oil can be removed (except the compressor, receiver dryer and expansion valve: the compressor must be removed from the car and all oil should be drained from it, and that oil must be measured; the receiver dryer needs to be replaced whenever the system is opened for a long time, and the expansion valve, if clean, can be put back, otherwise replacing it surely won't hurt; never flush these parts). Since you didn't mention a compressor seizure and that the lubricant oil is designed to be soluble in the refrigerant, a closed loop liquid refrigerant flush (one where the machine maintains a steady flow of liquid refrigerant through a part for a certain amount of time, separating any oil that dissolved into the liquid refrigerant in the meanwhile) might be the answer (a compatible RRR station or dedicated flush machine is required for the job, along with the required adapters so that each system part can be flushed away). Your best option is to ask a licensed AC professional for an oil removal to be done through a system closed loop liquid refrigerant flush.
2,3) For this, look for the compressor in the engine bay and check the compressor's label. The oil type and quantity is usually written there, especially if it's a Sanden compressor (some Googling yields me what looks like a Sanden TRS scroll compressor for that car). Unfortunately, i don't know them. But, always begin by having a look at the compressor's label and identifying the car's compressor's model. Then, putting the oil back in is a procedure specific to each compressor. With some, you just put the whole system charge back in the compressor and then turn the clutch hub a number of times by hand so that it won't slug itself to death during startup; with others, you need to insert a precise quantity of oil in each part of the system and then let the engine idle with the AC on on max cooling for some minutes so that nothing would seize up. Again, a licensed AC technician is the best option.