Video phones and asterisk?

hi, I am looking to use the GXV-3000 video phone from Grandstream with asterisk.

here is what i would like to do.

deploy about 17 of these phones as main extentions in a building on its network. install an asterisk server on the same netwrok. use 4 viop providers with a bring your own box option so i basically wont need any cards in the asterisk server ( am i correct on this ) using a t1 line that the current internet runs over.

i would like to be able to do the folowing things, does anyone know if these are possible.

when video phone extention 11 calls extention 13 i want video to come up on both phones.

i would like to deploy some of the same video phones at a remote office and use the same asterisk server here, will i be able to do the same video extention to extiontion ?

would the video traffic run though the asterisk server or world the phones made a direct video point to point connection ?

what about 3 or more confernce calls?

thanks

Great topic, I would love to know the answer to this even though I hear the GS phone is very primitive.