Care and feeding questions:  (1991 E-350 7.3L Diesel, non-turbo)   
1.  If I pull into a McD's and run in to grab lunch to go, should I leave it running?   
2.  Pulled the air filter out (PITA) and discovered that the dealership changed it already.  But I noticed the intake that the filter can sits on (throttle body?) is very oily.  Should I clean that?  If so, what should I use?   
3.  Fuel filter is impossible to get at.  Partially because of the extra wire harnesses for all the ambulance stuff.  Should that filter come off with my fingers, or should I need a strap wrench?  Also, when reinstalling the filter, should I use a strap wrench to put it back on, or spin it on like an oil filter?   
4.  Belts are LOOSE and there's no good way to tighten them.  There's a pump on both sides of the engine.  I assume one is power steering, what's the other?  Fuel pump?  And which one is on the driver's side?  Is there a trick to tightening the belt for the driver's side pump?   
5.  Not quite a diesel question, but:  I haven't worked on a truck like this before.  Can I replace the shocks with it sitting on the suspension, or do I need the suspension to be at full droop?   
Thanks again.