@Bella Dea,
Regarding your question 1. The Droid will NOT make a call via a bluetooth headset. From what I gather, currently, there is not an Android OS based phone that allows for voice dialing via the headset. I have been researching this highway safety shortcoming since I bought my Droid in November. From bits and pieces I've been able to put together, the Android OS has the ability to execute this feature, but for some reason Google has it turned off. I've yet to find any information as to why. Considering many states and local areas ban cell phones while driving, I find it odd that bluetooth voice dialing does not work. However, the bluetooth headset can make a "last number dialed" phone call. Go figure. On most cars equipped with factory bluetooth, the Droid seems to work ok with them. The only complaint, many times the contacts do not move into the car's bluetooth phonebook. As to your question 2. I can answer my Droid with my headset. However, it does not ring in the headset, only the phone rings. To add to the previous post regarding question 4. Just pressing the power button for a second will turn the screen off. Pressing the power button again, the screen will come alive. You will have to use the unlock swipe once the screen turns on. Hope this helps.