Like everyone else says, I would prioritize what is most important for you to see. If you say Munich(since you pickup there), Poland, Nurburgring, and Switzerland; that is plenty for that length of trip. Italy should be an entirely separate trip altogether(and I wouldn't waste my time with Milan either). Just looking at your itinerary, there is no way I would drive 6+hrs from Prague to the Nurburgring, and then feel like I would have the energy or concentration to get on the track. You will completely burn yourself out within a week.
2003 BMW M3 Vert | 2005 Volvo S60 2.5T | 2006 Scion xB | Past: 1986 MB 190E 2.3-16