Corsi and Kelly were conspiring with each other over Assange, and Stone was in that loop, as well.
The indictment is a rather fun read. This is all leading up to a way to legally enter wikileaks documents into court. I am not familiar with how chain of custody laws work, but if Wikileaks were subpoena'd in regard to a case and they handed over documents, it's possible that PRISM and other intercept methods could be used to bolster the authenticity of what wikileaks has, proving a sort of chain of custody.
Since prosecutors can't peruse the intelligence agency intercepts for evidence of crimes, they must rely on public information to issue an indictment or subpoena.
Legally speaking, the democrats signed their own arrest warrants when they commissioned the special council. The legal options were very limited until this point, because of the challenges with getting investigations started. However, the Russian Collusion narrative is exactly what allows these investigations to push forward and pull evidence into the public sphere for prosecutors to act on.