The modulator doesn't need to hold vacuum for five minutes for the trans to shift properly. I have never heard of this criteria. I suppose that the check is valuable though as the possibility to suck trans fluid or other debris into the line (and valves and orifaces) if there is vacuum flow.
The second question is harder. I presume you are talking about the vacuum proportioning valve. I presume the instructions are to disconnect the valve from the throttle linkage so that the valve can be moved with the vacuum (engine running) without the engine reving. If the throttle moves in this condition you really haven't disconnected it ("I moved the lever on the regulating valve to full throttle position (or in that direction anyway) and the engine was no longer at idle"). The point to this is to see the range of vacuum control. With a vacuum source (engine running) the vacuum to the modulator should go from high (10in or higher) to zero as the valve is moved by hand. The valve is disconnected by either removing the plastic clip at the top or by popping off the ball socket at the bottom.
And YES if your vacuum were to increase instead of decrease with throttle your shifts would happen earlier.
Bosch Master, ASE Master, L1
33 years MB technician