You can use a program like ORB to artificially give you more memory. This way, you can have access to anything you want. But no, there is no memory card slot.
ORB is a program that streams all typed of media from an internet connected PC to your phone. More info at orb.com
You may purchase additional memory cards, visit your local sprint or radio shack store for more help.
Yes, but to my understanding, the Samsung A900 does not have expandable memory. I think you are thinking of the Samsung A920 that has TransFlash memory.