Welcome to the forum and congrats on your new e34.
I have seen that strange behavior while starting in cold weather in my car too and I think it is normal. When you start it cold your DME will initially give more fuel and car will rev inbetween 750rpm to 1000rpm. At one point DME will try to reduce the rpm to normall 550. DME corrects its decision if the engine is going to die. I think it is just a trial and error method tried by DME based on some input. I wouldn't worry about it.
Did you figure out which fluids are leaking?
Arun