Unless you're going to be buying dozens of the memory cards, I wouldn't worry about the format. Just get one or two that are large enough for your needs, and a reader with a USB interface, and you should be fine. The cards will likely last far longer than the camera.
From your description of the cameras, it really sounds like you want an SLR though. If you don't want to spend that much money (and I probably would wait if I could), the point-and-shoot cameras are pretty amazing these days. I recently got a Canon SD700 IS for my wife for Christmas. I can't report on how well it works, but I was shocked by how tiny it is. It would be trivial to take anywhere.
The P&S cameras seem to have dropped in price quite a bit in the last few months too.
Things seem to be changing pretty quickly in the digital SLR side of the market, at least according to the [link|http://news.google.com/news?q=digital%20slr&ie=UTF-8&oe=UTF-8&client=firefox-a&rls=org.mozilla:en-US:official&um=1&sa=N&tab=wn|news stories].
To sum up: 1) The memory format should be about the last thing on the list. 2) It sounds like you should wait a while to get something closer to your wants.
My $0.02. HTH a bit. Good luck!
Cheers,
Scott.