Sovi3t, the choice is up to you. If you look at the links on OOC front page, you can see that there are already profiles from previous players of Orsinium/Skyrim. You can reuse these or create your own.
Panda, Dragonborn (and all champions) can be canon, but only to an balanced extent. Hyperdrive has a Nerevarine ruling his Morrowind, however, the guy is just a powerful warrior king, not a CHIM (CHIM reserved for moderator usage
) wielding juggernaut. The same applies to your Argonian champion, more detail on that in my PM.
On the issue of champions, you're allowed to have 1 per country/nations/state. If they're not established in previous canon, they will be only as powerful as regular mortals.
At last, Darkwolf. Just letting you know that communication is not instantaneous, as traversing Tamriel, even between neighboring provinces, would take days. Your messenger is not Usain Bolt, he needs time before before delivering his messages.