For stiffer suspension you can try Koni struts. everyone says the KYB and Tokico have soft yet firm OEM feel.
The Eibach springs are European and i think H&R are too. Tanabe is what most people like due to cost and workmanship
For coilovers you can get the Tein coilovers and EDFC which allows you to adjust the height in the car.
Bigger wheels will affect the handling, i'd study offsets and tire sizes on Clublexus.com
From what people say Euro cars are made for Autobahn driving. very fun to drive, good handling and fast. Jap cars are made for reliablity. also fun to drive, fast, but made for American driving (65mph on I-70) but you can push a Jap car.
I would say lower it and get larger wheels. BMW's are not much different except for the quality of parts.