It's good to hear you're doing it properly.
As far as vacuum pumps, I've made some from discarded refrigerator and dehumidifier compressors. Once the unit is removed from the refrigerator, use the suction line to pull a vacuum. Works well enough. New one can be bought from the internet for roughly $250. (Still a savings for the do-it-yourselfer, compared with having this job done for you.) Try ackits.com or caawparts.com for more information.
A/C compressors, per se, don't get flushed during a conversion like the other parts. You simply drain as much oil as possible, turning the shaft a few times during draining. Then run some new PAG oil through the compressor to wash out the old oil. All other passages, with the exception of receiver/drier, orifice valve, and any filters, get flushed with solvent.
To charge the system with oil, put half the required amount in the compressor, and distribute the rest throughout the system. That way, the a/c system wont be starved for oil during startup.
95 E320 Cabriolet, 131K