Before I give you feedback, I am moving this topic to the Tutorial Panel. This is only because this forum is reserved for announcements and important guild news. Furthermore, if you are planning to document your progress, this would be an excellent candidate for helping newer players get the gist of what they're doing. Depending on how this turns out, I'll turn this into a sticky.
Now then, for your promised feedback.
For Sheef: I agree with the idea of immediately changing him to a thief. That will bring his speed up. Converting him to a Ninja afterwards will get you Double Sword which will allow you to learn abilities faster. And your speed will skyrocket. Personally though, I'd go for the Fighter moves, they're slightly less powerful, but two are ranged and it your offensive stats are good, you don't have to be anywhere near your enemy. :3
Montblanc: I actually left him as a primary magic user, but Gunner works too. I might change him to Thief immediately though to get his speed up. It lacks if you don't. I was just lucky.
Human #1: A good idea to keep a magic offensive unit. Great idea!
Bangaa #1: I don't usually use Bangaa, they're too slow and that combination is the slowest of all. XP Nut you'll have one strong unit, so it might be worth it. :3
Viera #1: I like this combination! Great idea!
Nu Mou: Morpher is a good idea, but you might want some white magic added in. Granted, your first Viera can handle that. But honestly, two healers are far more effective than one.
Human #2: A hunter is a good thing to have, but keeping him strictly as Archer/Hunter might not be a good idea. Perhaps teaching him soldier or Thief abilities might be a good idea. Or a job with out any long range abilities, just in case.
Viera #2: I'd suggest starting as a Fencer, then moving on the archer, sniper. But actually, Assassin might be better. Assassins have some wicked moves, I'd definitely suggest an Assassin.
And finally Bangaa #2: Good idea. White Monk is the fastest Bangaa class. :3 Do some good leveling up with it. Good combo.
If you have any questions, please, do not hesitate to ask!