Well, I found both solutions by myself. Please mark thread as SOLVED. Here they are:

1) Crash by Facebook contacts was due to the existence of some special characters in the names that were added after activating the Facebook chat and contacts. In my case, a few "ö" were the problem.

- Edit the contact and add a plain name without special characters in the "First Name" field. This will override the Facebook nickname and won't cause a crash. Do it with every contact with special characters (i think, unicode-dependant ones).

2) About the A2DP auto-connecting by default; I found a solution, but it may cause some devices wich don't force-connect A2DP by their sides won't show the profile (i don't know).

- First gain root access via SSH. Install "Nano" from the store, and then do this:

http://talk.maemo.org/showthread.php?t=79645

- Log in with your SSH client with root account, and search for the "audio.conf" file in /etc/bluetooth folder.

- Open the file and edit the "#AutoConnect=true" setting. Remove the # and change it for false, so it now reads "AutoConnect=false".

-Save the file. Remember, you can't save it if you don't have root privileges.

After this mod, the stereo system will connect the HFP profile and won't show a STREAM (A2DP) option. If you want to use A2DP streaming, you must go to the Bluetooth settings in the N9, search for the device you're connected to, and then hit disconnect and immediately connect again. Forcing the connection with the phone will enable automatically all profiles including the A2DP so you can use it, like before, but the auto connection coming from the stereo won't start the A2DP profile.

Notice: This mod may cause other devices like stereo headsets to alson don't connect to A2DP, so you must do the same disconnect/connect trick to use it.

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I think a proper solution would be to modify the profiles' priorities so AD2P will not override the HFP when connecting, but still making it available to use instantly.

Any other help to achieve this would be awesome.

Thanks and bye!