With how small the Vita TV for those who work in a game company for example could literally bring it with them to work and hook it up there if they wanted. Granted they would need a DS3 though
Yes if your friend owns a Vita TV and you are there with your Vita you can play together.
It also uses that Ad Hoc Party thing, but Ive never used it myself and always am hearing how buggy it is. No one in the GE2 thread posted about trying it yet either.
Example below from TGS 2013
*Edit btw if the pic is broken, currently something seems wrong with imgur so just click on the broken image to watch the video.