Ok, simple enough question...if i give a herd the vitriolic totem that gives them poisoned attacks. Now, against ethereal creatures/creatures that can't be hurt by non-magical attacks:
do poisoned attacks affect these creatures?
if not, would having the magic totem count as making all the herd's attacks magical?

thanks in advance

Poison is not magical, no.

Although if you can find a magical attack that is also poisoned (none that I know of) then poison would work on ethereals.

Serpent Staff on Tomb King Liche Priests for that 25pts of 1 attack poisony goodness!

Since its a magic banner...wouldnt that mean attacks are magical?

nope, not unless stated in the description of the item. Just like you don't get magical attacks on the charge for having the beast banner, only +1 mundane attack.

The cheap lizardmen item which gives mundane weapons poison and magical attacks springs to mind too :)