Well, here is my two cents on these questions.
If, as you said, the cameras are basically equal other than the MP difference, then you should absolutely not buy the 12MP camera. Your pictures will actually be worse than with the 7MP. This is due to the camera trying to pack 5 more MP's into the same sized sensor. This leads to more "noise" in the photos which makes them look much more grainy. So my advice here is to enjoy the camera you have and don't give in to the manufacturers "more MP's equals better photos" advertising schemes.
As far as the memory card is concerned, I have no idea what you mean by "is it more for movement". I have not looked into this card, but if I were to guess, it probably qrites and reads faster then it's predecessors. Just a guess. It does not have anything to do with movement at all. It's only job is to write the data that the camera sends to it and then send that data to a computer. If it is faster at writing and reading, that may be a good thing or it may not matter. If you aren't having troubles with the cards you use now, then my advice would be to stick with the ones you are using. Chances are you won't need faster writing speeds. Faster read (to the computer) speeds are sometimes nice to have though. The basic answer to this question is that it would work for all your needs, but I'm not sure it is necessary.
I hope this helps your dilemma somewhat. I'm sure that others will give advice too.
Andy
