And if the WaPo had already tried to claim in June that the only hacking of the DNC was by Russians, a story which was basically planted by the DNC, then it's very likely the same people behind that scheme would also try to tie Trump to the Russians.
While I see that as very likely, I don't think Strzok was any kind of mastermind. He was more like a meathead with enough liberal bias to go along with the scheme. The masterminds were more likely as you inferred the ones sending millions of dollars to Crowdstrike, Perkins Coie, and Fusion GPS.
Who exactly, it's not clear yet. But if FISA applications can only be signed by the AG (or Deputy AG?), it's someone operating up around that level, or higher. Probably one of the Clintons, or Obama, or one of their closest advisors.
FISA applications can be approved by any of the US District Court Judges appointed to the FISC by the Chief Justice of the USSC.