Yes, it can be strange, but you should think of them as multiple lives and/or tools for elemental weaknesses. !but yeah, a healer is quite useless in pve mode.
It's... different. While the chinese version grants much more pull/day (the jp doesn't give diamond at all from dailies), the JP version doesn't bother with shards in the gacha, you get immediately a character. I think the chinese one is still more F2P friendly for several reasons. But yeah, the JP one has more chance to be the one Nutaku will use (closer to what they usually do).
However, the good point is the fact 3* can get as strong as 5*, more or less. At least, that's what I believe comparing the BP at low lvl (it may change later, or the skills may be broken).
EDiT: Checked the trailer once again, and the version presented is the chinese one (1* to 3*), so, let's get our hope up. If they don't butcher the daily quests, the game will be very friendly.