"Lifetime" fluid refers only to the lifetime of the transmission, which would be shortened from not changing the fluid. Change the fluid in your trans and differential. Only leave the fluid in there for YOUR lifetime if BMW provides a warranty to cover that time period (and they don't). And if it's been more than 2 years, change your coolant, and change your brake fluid.
I am now at nearly 125K in my 1999 540/6, and fortunately my radiator upper hose was reworked before I bought my car. I've owned many hi-miles cars, and I think you only need to take an incremental approach to preventive maintenance replacement of things, as long as you also address those items specifically called out to be replaced at 100K miles (different items for your car, but in my case included spark plugs and O2 sensors).
Rear ball joints are generally worn out by 100K (I replaced mine at 110), and most front shaking is caused by worn bushings on those front components. Just replace what's needed to stop the vibration. Others may disagree, but to me the incremental approach is better than spending a lot of money replacing everything at once. For instance, wait until a wheel bearing starts to make noise, then just go ahead and replace L & R side bearings, and so on.
Alternatively, there is an e-Bay vendor in CT who sells entire front end rebuild kits. His I-6 E39 kit is $449 and includes both lower wishbone pieces and bushings, tie rod ends, and sway bar end links, for both sides of the car. That's one way to get it all at once and not kill your self too much.
2006 Honda Odyssey EXL-RES
2006 Honda Accord V6 EX-L Sedan
1999 BMW 540i 6-Speed (Sold to M3UOND on 9/21/06)
1991 Honda Civic Si - Occasional Beater