search for pics of DTM 190's on google images for what i mean for wheel style, the oldschool racing bottlecaps look so awesome.
as for lowering the car, if you want to keep the same "feel" dont lower it too much. when you lower a car it changes the geometry, it takes a bit before it starts to have a negative effect on the geometry but i guarantee that 90% of the cars in this thread handle like shit being as low as they are. but lowering it like 1-2 inches should be fine. those cars are pretty low stock anyway.
just really focus on getting quality suspension aimed at performance, not looks. and if your getting struts and springs, dont cheap out. if you can, try to find coilovers. though i dont know much about mercedes aftermarket stuff, 1000 should get you a decent set. from my experience, 1000 dollar lower end coilovers feel so much better than really nice struts and springs.
stiffening it up wont ruin the feel it has now, just make that feel more noticeable and sensitive.
dont go super stiff though, track suspension on a street car is a bad idea. your going to be skipping all over the place struggling for traction on anything bumpy at speed.
sway bars and poly bushings are also a very good idea. it will make just as much of a difference as coilovers.