The relay app tool; does it require the TV at all?
Sorry for the late reply.
When you're playing it doesn't need the tool, but you do go in an select your room, lobby etc. in the beginning. Also any text chats show up on the TV.
I was mostly concentrating on the play =), I'll try to pay better attention next time. I know the TV showed the text chat on the left side of the screen, a full column taking the whole left side. Lower right was a little box showing all the hunters I believe, and the rest of the right side was an option menu, which I didn't really explore. I remember friend list, chat history, and network options...
The gamepad has a button to bring up the keyboard, a button to turn voice on/off (which I used as a push-to-speak for awhile, but then just left on) and that's it. So it's possible they could move a lot of the TV stuff to the pad in a patch.
It worked really, really well. Pick your lobby (or whatever) and then you find it on your 3DS in the friend section and join.
I played with the gamepad sitting on my lap and used it as a microphone.