1 - As the images on the first page show, both of them support SDHC. SDHC's limit is 32GB officially. Above that might work, but don't count on it. DS games are tiny (for nowadays) anyways, you can fit 75-100 in 8GB. 2 - The DSTwo is the only cart in the list with it's own special homebrew. Any cart can run normal homebrew, but only the DSTwo can run it;s own special homebrew, so the capabilities of the DSTwo are better than all the other carts. 3 - Either or. You change mode for DS games by holding Start/Select while it's booting up, and it's the same for flash carts sine the 3DS detects and treats them like DS games. 4 - The first post... the entire point of this thread is the start, which has the charts.