Cooper & Hunter Hyper Heat 9,000 BTU Single Zone Wall Mount, 230V, R410A - Ductless Mini Split Air Conditioner Heat Pump

The system is working fine, but the instructions are not very clear. Most importantly, the system comes charged, so it is impossible to pull all of the ambient air out of the system. Also, I had hooked up a vacuum pump to the system to evacuate before a charge, and when I opened the valve on the unit, high pressure refrigerant went into the pump, and I lost some refrigerant, and did some minor damage to pump. Instriuctions should have mentioned that the system was charged, and provided direction on what to do. Should I have purged the lines some way?