First off, the signage throughout the WDW resort complex is excellent, IMO. I feel as though I can navigate very easily on property, as long as I know what area the destination is located. For instance if I want to get to the Contemporary Hotel, I want to head toward the Magic Kingdom. All Star Resorts are near the Wide World of Sports complex (-ish), and so on. You should be fine driving. If you want to reach a destination off property (grocery, etc) just ask the concierge desk at POR.
Second, whether to drive to the parks is a personal decision. If you drive into WDW and need to drive home, you may feel like using the WDW transportation system while on your vacation. From POR, there is boat service to DTD, which I recommend more so than driving due to a lack of parking options there. However, bus service is pretty good and usually takes from 15 minutes (bus arrives when you get to the stop and heads straight to the nearest park) to about an hour (long wait for a bus or during super peak times). I find it takes about 20-35 minutes on average to get around via the bus, so it isn't bad.
Third, if you are at the Magic Kingdom and plan to head to the Contemporary for dinner, I would just walk. It takes about 10 (or so) minutes to walk between these destinations. If you want to bus into the Contemporary, just take the line to the MK then walk from the depot (same distance). This is also a good way to visit any of the MK resorts without parking at the TTC. The roads around the MK resorts are a bit complicated, and if you take a wrong turn you'll be exiting the area on their thoroughfare pretty quickly. As such, I recommend looking up the map on Google maps just to get familiar with the route.
If you drive to the Contemporary, just head to the MK, but stay in the right lanes. Once you hit the toll booths, tell the attendant you are heading to the CR, then get to the right. The road that services the resorts is a two lane job on the right hand side. Usually, I just follow the buses to the route. The CR is up and to the right, while you'll need to turn left on Seven Seas Lagoon Rd to get to the Poly or GF. Not hard, just need to pay attention. If you aren't sure, just ask the toll booth attendant.
In the end, driving around the complex versus riding the Mickey buses is a personal call based on time of day, desire to get out of the area quickly, and how much time you have to transition. Sometimes driving in your own car is worthwhile, and sometimes it is a hassle. I do recommend not driving to DTD, though. Just take the boat.
