Yes, you can still trade while in peace mode. You can always change your alliance affiliations, even in peace mode.
So, you want to make your own alliance? I'm not going to say you can't do it, but I just want to tell you it is going to be VERY difficult. There are already many well-established alliances, and it will take an Ungodly amount of effort on your part to create a decent alliance.
But in any case, if you want to start an alliance, this isn't the forum to recruit on, go here:
http://forums.cybernations.net/index.php?showforum=24