I'm looking a relevance and deciding what pieces fit where in the chronology.
Otherwise, STOP SPENDING MY DAMN TAX MONEY ON FOOLISHNESS.
Alrighty, here's a primer. In early 2016, one or more of the republican 12 candidates started to develop opo research on Trump. When the candidate failed to gain any traction, it's likely(unprovable without a warrant) they gave that opo-research to the Clinton campaign in a fit of spite. The Clinton campaign in mid-2016 took the scraps of the Trump dossier and hired a political hack ex-MI6 guy to punch it up. Over the next few months, he and some soon discovered political operatives on the left(Cory, Sid, Podesta group) planted some gossipy lies among several truthful negative pieces, and wound it all up in the current Trump dossier. Clinton - being the ex-sec of state, took the product of their collective imagination to the DOJ and said - 'hey, look at this nefarious stuff we found on Trump. You should present this to the FISA court, and get a warrant to snoop on the,,, ahem - Russian who are meeting with Trump campaign operatives'. In mid/late 2016, the DOJ not wanting to get spattered with shit advised top people in the FBI to vet this info from Clinton in the dossier. The FBI obliged, and likely(but not provable) endorsed most of it, or was neutral on some, and positive on other parts of the missive. DOJ then advise FBI it could/should present to the FISA court for an expansive warrant to gather up intel on the Trump campaign. The FISA court, based on this dossier, and maybe some other supporting intel from the BO CIA/FBI watching over some minor Russian lawyer decided to buy-in and granted the warrant. Strangely, all this take from the warrant authorized spying on the Trump campaign in fall 2016 made it into the main-stream media. Hmmmmm, isn't that convenient. It also made it somehow to the Clinton campaign, which started bandying the "Russian collusion" angle.
FF after the election, and the dems are hanging on by a thread. They decide to go bold, as they have nothing else to do after losing the election and start leaking all this Russian, 25th amendment, unfit for office, conspiracy, obstruction stuff before and after the inauguration. Heads start to roll in 2017 spring, and now we are getting some of the background on where this made-up dossier came from, the players behind it(Cory, Sid, Podesta group), and how and why the take from the FISA warrant seems to be splattered all over the news constantly. We KNOW some of it was released by Comey(FBI), because he admitted it under oath. We know also that Clinton had, and forwarded to the DOJ because the DOJ lawyers won't talk about how they got it(but the DOJ sure is a sieve when it comes to leaking Trump gossip). We think, with decent amount of surety that Mueller investigation was based on part of the dossier, because it was the DOJ which started the special prosecutor process, and they didn't do that with anything from Russia, or Trump campaign. Where did the origin of the SP get it's info? FISA court? Where did they get their info? Trump dossier. Who had the Trump dossier prepared? Clinton, and DNC campaign.
I hope this helped. The Nunes memo, and the next one coming out basically lay out the some of the players. Although more of them are dribbling out. It is a concerted effort on the part of the Dems to use every disgusting, dirty trick(ala Watergate) to discredit Trump. Which would be ok, if there was any facts about the Russia deal. Mueller is sweeping up every tweet, statement, document, and gossip he can to justify his existence. Which is what SPs do, just as with Slick Willy.