Can I use Elemental Chat with my peers, or is this mainly used for testing?

If your peer(s) have a HoloPort, then you can certainly test with them. However, during this first phase of testing it is only open to HoloPort owners. The next phase, when hosted Elemental Chat is made available via a browser, all Alpha/Beta perk purchasers from the IGG campaign and Nano owners will be invited to participate.