When you start you will notice the bubbles are much smaller and more abundant, that is C02. After awhile, typically when you can hold around 17" you will notice that the bubbles are much bigger and less abundant, there may be a little gas being pulled but most of it will just be vacuum being pulled through the wine and in my eyes you have degassed thoroughly enough.
As for the brake bleeder, there are actually a few variations of this. 1 is the 1 I have which is plastic and does work well, the other 2 are metal and I have never worked with either of them. The metal 1 that looks exactly like mine is rebuildable. As for the red one, Im not sure if that is rebuildable.