You have found an awesome awesome deal assuming the car is in good running condition. wow. lucky
there aren't too many major problems with it, other than the muffler... it has weak thrust arms and bushings that will cause your car to do a little shimmy at 55mph and go away at 60mph, no big deal... can be fixed relatively cheap by putting on the parts from a e32 750iL.
there are a few electronic issues, like the gauges will start to burn lights out or become erratic, but that is also easily fixed if your not afraid of a little DIY.
pretty much every question you need answered should be able to be found here : http://www.bmwe34.net
enjoy your car! looks great and awesome deal!!