The 1989 Oldsmobile EGR valve is located on the top of the engine, near the back. It is quite simple to change.
Yes, as long as the exit point of the hose is lower than the input (suction) point. Once it is, you have to "bleed" the hose by sucking fuel through it; the gravity of the fuel falling out of the hose at the outlet will perpetuate the suction at the inlet.
I believe it is on the block where your engine coolant runs into the block from the radiator. There should be two wires that run to a plastic-like sensor.
Check the emission label usually located on the top of the radiator or on the core support just in front of the radiator. You will see a diagram of all the vacuum lines and emissions equipment. Generally-the EGR valve is located near the throttle body.