1) Depends on your car, check your specific car forum to ensure that an extractor will work for you and it won't mess things up.
There is always old oil in the system. If your old oil is so bad that the remainder is a dealbreaker for you, then your oil was already way past due.
Engineers don't need all the oil being exchanged, some cars actually get more out via an extractor then the drain plug so vice versa is true too.
2) mityvac 7201, just because it has a dispense feature so you can dispense the oil back to a transport container for recycling. Be sure to check operation with water before you go at it with oil.
Like any tool you need to learn how to use it. If you just threw an idiot a torque wrench and say use this to do a traditional oil change, they could mess up the oil change; just the same way some folks can mess up using an extractor.