Welcome (to the forums and to Krautland as well)
Looks like you've come a long way with your car and put a lot of effort and money into it.
I can't tell you much about the exact procedure in order to get your car road legal in Germany, but what I can say is that it'll be rather difficult with all those aftermarket parts. First you'll have to pass a thorough check by the German TÜV in order to get your car registered and insured. The TÜV engineers will probably want to have certificates for every security-related part that was not on the car when it was new from Toyota. This applies (e.g.) to the rims, suspension, brakes etc.
Some (mostly German) manufacturers of aftermarket brakes, rims and suspension parts provide certificates accepted by the TÜV, but that's very rare and you most probably won't happen to currently have any of those parts on your car.
Everything which might change your power output or emissions will make even more problems since the TÜV will want to do some costly tests and measurements (that's if they don't go the short route and just say "no way").
After all you probably could get your car street legal in theory, but this would take a silly amount of money. That's why only very few people go through that hassle.
The aforementioned thorough TÜV inspection is due upon first registering a car after importing it and a (only slightly) less stringent inspection is due every two years.
Most people with modified cars over here just resort to converting all the relevant parts back to stock before going through TÜV inspection. This is kinda risky though since in case of an accident, your insurance will search for anything illegal on your car which might have had an effect on the outcome of the accident. If they find something, you're screwed.
You might want to get in contact with a guy who is said to have many hard-to-find certificates for aftermarket parts:
http://www.rhd-speedmaster.com/index...d=1&Ite mid=2
He's specialized in importing cars from Japan and the UK and get them road legal here, so he might be able to point you in the right direction.
Good luck...