I'll answer with what I see in these fields…

Stoneskin: It seems like it would be a bit counterproductive for a mage to be completely incased in stone, as the name suggests. I've always invisioned it to be more of a crystalline field around the mage, that chips away as damage gets directed at the mage, until it breaks completely.

I personally think they would be encased in stone… lol. But the stone would be light enough for them to move it.

Aquaveil: Would this really be just a constant sheen of water over the mage? And *how* does it stop the mage from getting their spell interrupted?

Sheen of water yes.
How it stops: Magic takes certain words to be chanted and certain hand movements. The water would prevent the mage from losing focus on the hand gestures

Protect/Shell: Maybe more of a protective barrier? It doesn't block damage, but sort of mitigates some of the damage before it can hit?

Agree…

Blink/Utsusemi: So how do people handle this? After casting, you have clones that vanish? Or do they only appear when you're about to take a hit, they take the hit and then vanish?

From wikia: "Utsusemi" can also be translated to "Projection." Which makes sense to the Ninjutsu since you "project" three to four images of yourself to protect yourself.

Basicly copies of yourself appear and are mistaken as you/take a blow for you…

Blink however is different from Utsu as, the way I'm seeing it, the copies aren't perfect and easier to avoid hitting.

2hr: Some of them are pretty self explanatory, like Perfect Dodge and Invincible. However, what about Manafont, Azure Lore, Astral Flow or Trance?

Astral Flow: Summon the Celstrial beings power into the Avatar?

Manafont: (Wikia) …allows a Black Mage to awaken the magical power sleeping within their body and cast magic spells without expending MP…

Me: They use a secret black mage cult spell, Manafont, that allows their bodies to excede normal limits, IE: cast without MP

Azure Lore: Blue Mage thing. Not my field… *growls at the BLUs*

Trance: They use this dance and it puts them in a Trance like state.Nodem

I agree with most of sae's idea, but for Stoneskin I (after discussing with Avi about it a while ago) considered it to work sort of like Gaara's sandskin. You wouldn't see it on him until he'd get hurt and lose some of it. Works better than the picture of a mage's skin covered in rocks at least.

As for Azure Lore, all I can think of is that the BLU focuses beyond his limits, to the point that the spells are enhanced, sort of like Divine Seal and Elemental Seal.. which is why I always think it should be a normal JA and not a 2hr (a good BLU 2hr would one temporarily allowing you to access to all your learned spells and traits). I guess we can justify this with the fact that blue magic, unlike black and white magic, puts a higher stress one the body and the mind, so it is harder to enhance compared to the other magic classes.Kenjii