I had a hard time choosing between IV and VI, but in then end IV was easier than any other for me. I didn't even find the hard version that difficult and I played a rom of it before the easy version.
That's bizarre to me, because I think IV is probably the hardest, certainly top 3.
Only the DS version, though.
No, both. Getting through some of those places on the moon is a serious trial, even at high levels.