I know this is a dead thread effectively now, but as I have the phone myself now I can directly answer all the questions asked.
I have heard that people have had problems using this phone with a mac. All I want to do it transfer pictures and music. Can I do this? With a micro SD card?
You can either put data onto a Micro SD card connected to your Mac via a card reader, or simply USB/Bluetooth data across using the normal Finder/Bluetooth apps. If you are relying on your phone's internal memory, however, you cannot access this memory via USB - you will have to send files via Bluetooth.
Also, with this phone can you set MP3 songs at ringtones? And if not, is there any app out there that converts MP3's to .AMR?
Yes, you can, though strangely not as message tones.
I switched from a Sony Ericsson T610 to a Razr last year, and the feature I miss above all is the ability to send SMS messages from my computer via Address Book, paired to my phone via Bluetooth. Can anyone confirm whether or not the D900 can perform this task?
It doesn't really work, no, frustratingly. It gives the impression that it is working nicely - when you click the Bluetooth button on the Address Book window it highlights blue and says it is connected to the D900. However the sending and receiving of messages do not work, nor can you dial/answer using your Mac.
You should check out mirasoftware, they have software that should allow you to do what you want.
Certainly BPE 1 doesn't work - it gets confused when counting the messages on my phone. For obvious reasons I'm not willing to buy a licence to test version 2 - I'll wait and see what they claim it can do whenever it gets released.
So overall the D900 plays pretty well with OS X, but is tantalisingly close to being perfect. If it gets sorted with the Address Book I'll be a very happy man, and if not - meh, I'll survive.
🙂