Questions about real DC-9-41 fuel system?

Hi,I've been working on a fuel system for a DC-9-41 sim. thanks to many who have helped answer many questions, but I have a few more about how the real system works.1) When the aux. transfer pump is triggered, while in "Auto" mode, will it keep transfering fuel at a maximum rate until it's empty or the center is full? ...or will it keep the center at an even 900 Kgs as long as it's capable of doing so?1b) what is the rate of transfer for the aux. pump?2) when the aux. transfer pump is set in the "Test" mode, is this a momentary switch or will it stay in the "On" position? does it actually transfer fuel or just illuuminate the annunciator light?3) What are some real life reasons why you would NOT turn on a Fuel Pump? One basic assumption would be on short flights when a tank is empty. But, what are some other reasons? Will engine pumps only, be enough on the DC-9 to keep the engines running after startup?4) If no electricity is supplied to a fuel system switch, will they auto-spring into the "off" position? ...or will they stay in the "on","test" or "Auto" positions with no effect to the attached device?5) Do water ice crystals slowly clog the fuel filters or does this happen instantly? I have read that on other aircraft systems, the annunciator light turns on when a 3 psi pressure differential is detected at the filter - is this also true on the DC-9. What is the average time-lapse for an engine shutdown if fuel heat is not administered after a filter press drop is detected?6) when a fuel heat switch is set to the "On" position, does this trigger the 1 minute timer or will it stay on until the switch is shut "Off" 7) when in "auto" mode, will the heaters come on per the 1 min timer when the "..filter press drop" annunciator light comes on? or is "auto" a strict 1 min on 30 min off device? (..or is it 1 min on 30 sec off?)Thanks,John