Well I think from a "best for peace and stability in the world" perspective, them somewhat repairing their relations, but not to the level of allies agin would be the best case.
Even without the Cold War, China has been very careful to keep Russia at an appropriate distance. I imagine with the Cold War still raging, China would be even more careful to not get entangled in a Soviet alliance of any kind. There is zero advantage to China to be added to the US's list of enemies at this point.
Not really, while the Virgin Land Campaign required a lot of resources, it was still profitable, because it increased the USSRs agricultural output, and also helped developed poorer parts of the Union. And with GMO crops it becomes easier for a Virgin Lands Campaign to become more profitable.
GMO crops aren't a magic wand and it takes considerable effort (which costs money) to get good results.
And due to the fragility of the land you're talking about, it would at best be a short term gain that would lead in to a long term loss. Soviet style industrial farming was pretty brutal (basically, it's US industrial farming with added overuse of fertilizer and pesticide and more leaky irrigation).
Just sticking some GMO crops into the agricultural paradigm doesn't address the real problems with it.
fasquardon