If I were to take my sandisk out of my BB and put it in my old phone (ENV vx9900) would I be able to transfer the pictures that are still on my ENV to the disk and not lose any information currently on the disk?

Yes.

If you have encryption enabled for pictures they'll have a .rem suffix and cannot be opened by any other device. Not even a pc. Be sure you have disabled encryption for pics before transferring the memory card to another phone.

Options > Security > Encryption: Disabled.