Q: How do I access the cheat menu, soft reset function, etc?
A: These features are all in the ROM config menu. You can access the config menu by sliding a ROM to the left, or by highlighting the ROM and pressing Y. Directions on how to use cheats can be found
here. There is no way to return to the main GUI once you have entered the config menu, and the only way out is by shutting down. Also, soft reset currently can't be turned on; whether these will be fixed in a future firmware update remains to be seen.
Q: What's the difference between the standalone M3 Sakura loader and the Triple Loader? Which one should I use?
A: Since M3 Sakura currently has poor support for homebrew, the Triple Loader is offered as a way for you to load homebrew via the M3 Real and iTouchDS loaders, which both have excellent homebrew support. Which one you use depends on your needs and is a matter of personal preference, though it certainly can't hurt to have all three loaders on one card. For a better explanation, check
here.