Effect of raising rear of car?

Yup. I believe thast the downforce from the Superbird/Daytona rear wings didn't begin to produce downforce until around 60 m.p.h. Raking a car down on the front end will produce more downforce at speed, but also more aerodynamic drag. It is a trade-off and is best adjusted with trial and error on the track. On the street, however, any effects will be negligible until you get to highway speeds.

Handling and road racing cars are generally as low to the ground as possible to keep the CG as low as possible, which helps getting around turns in the road. Body roll is not your friend when trying to get a car to handle.