typically, with bluetooth devices there should be some type of auto connect option that allows the device to connect automatically each time it comes into range.
i think that's the auto connect option you've mentioned.
auto answer typically will automatically answer any call on that device without any interaction from you.
if auto connect is working correctly you shouldn't have to pair each time or have to hit the pairing button, etc.
some of my past phones with bluetooth have rang while connected via bluetooth, and some have not. seems to be an individual device thing....
those are some general points regarding bluetooth, i can't speak specifically to the dynavin's implementation.