Supernatural duskblade?

[Arz]

Does a duskblade's arcane channel turn the spell supernatural or just change some of its means of casting?

Does the Vasharan extra vile feat require prereqs or not?

[NunoM]

The Duskblade's "Arcane Channelling" CF is supernatural, but i don't see how it confers that same classification to the spell cast. It's just an alternative way of casting and delivering the spells (although it does bring some limitations, ex.: you can't crit with weapon-like spell when casting this way). But why are you asking?

The Vasharan extra vile feat is exactly like the extra feat for humans at first level, but must be taken from the list of vile feats. Like any other feat, unless stated otherwise by some ability or power, the character must be qualified to take the feat.
BTW, vile feats are all considered supernatural abilities, so they are subject to the limitations associated with them (see link above).

[Arz]

Supernatural abilities don't have components. I.e. costly material components. Also time to cast being changed to standard. There are some very amusing and not terribly useful things I can do with both on top of the nasty game breakers. Oh, and no SR too. Try this link: supernatural

[NunoM]

I'm not sure i follow... Perhaps you're confusing Supernatural (Su) abilities with Spell-like abilities (Sp)?
The only thing Supernatural abilities has in common with Spell-like, according to the link you provided, is the use limit per day, if any.

In the case of casting a spell using Arcane Channeling, you can use it indefinitely without AoOs, but you still have to provide the material components and cast the spell with a free hand, for example. That's one of the reasons why channeling using TWF, or a shield + weapon, style becomes a little weird w/o the proper feats to overcome the limitation.

[linklord231]

Does a duskblade's arcane channel turn the spell supernatural or just change some of its means of casting?

No. 

Beginning at 3rd level, you can use a standard action to cast any touch spell you know and deliver the spell through your weapon with a melee attack. Casting a spell in this manner does not provoke attacks of opportunity. The spell must have a casting time of 1 standard action or less. If the melee attack is successful, the attack deals damage normally; then the effect of the spell is resolved.

You're still casting the spell, except you're delivering it through a weapon attack instead of a touch attack, and it doesn't provoke.  The fact that the ability that lets you do this is Su doesn't transform the spell you're casting into a Supernatural Ability.