Just click download ODK. Done.
Will it use Java like Android or can we code for it in C++?
It is essentially android so its java again. Seeming as you can also use C++ on android I assume you can use C++ on the OUYA (Google the NDK). Its been said that unity will be supporting the OUYA (I assume its not really a drastic change from their existing android version). Monodroid should also work.
*Looks in wikipedia*They said themselves that actually all consoles will ultimately be dev consoles. Those who willingly paid 699 or above were paying for the first run consoles. As the first run was so small (about 1200 approx) they are going to cost alot more than mass produced consoles, plus your getting a clear plastic console unlike everyone else.
(developer models ordered during the Kickstarter campaign for $699 or $1,337 will come pre-rooted)