I think there is an option before taking picture on where to save them. If not then you have to do them one by one. Copy them then remove the MSD. Then you'll see those stored on the internal drive and then delete. I suggest you use a more advanced file manager as well. If you MMS or e-mail pictures from your P900. It will store them on the internal drive even if you delete the e-mails or MMS's. You can find it on www.My-Symbian.com and the great thing is it's free. If you can't find it PM me your e-mail address and I'll e-mail it to you.
You can store everything on the MSD and use them when you want. I keep my internal drive as empty as possible. Just remember to click all the media formats to be able to use them. You can find those in the options menu.
Sorry I'm doing this from memory. I don't have my P900 with me at the moment.
you just made me question my phone, but i checked it out again. All my mp3's are saved to Mem stick duo. I set the mp3 ringtone and called my mobile. bam! mp3 ringtone played! checked my internal drive, and saw that there were no mp3's in it.
are the mp3 ring tones not working for you in the external drive?