You are mistaken on what "verified" means when it comes to a FISA warrant application. It doesn't mean that every tip provided by a source has been independently corroborated. Rather, “verification” refers to the process laid out in the
woods procedures (please excuse the poor copy on doccloud) which requires Justice Department officials to verify that representations made in a submission to the FISA Court match the information in the FBI’s investigative files. If the application relies upon a source for some claim (Steele in this case), the documentation in the case file needs to support that the source actually said what the application claims the source said. “Verification” in this case doesn't mean the FBI claimed to have tracked down Steele’s sources to corroborate his claims. Rather it means that the FBI “verified” that when the application summarized what Steele had told the FBI, it did so accurately.
That's not relevant. If an investigation turns up evidence of another crime, investigators aren't supposed to just ignore it. If the police were searching a home for a meth lab and instead found bodies in the crawlspace they wouldn't be expected to ignore them.
According to the FISA applications, “the FBI believes that the Russian government’s efforts are being coordinated with Page and perhaps other individuals associated with” Trump’s campaign, and that Page “has established relationships with Russian government officials, including Russian intelligence officers.” That's plenty reason to investigate.
He later told
CNN
And before anyone goes OMG FAKE NEWS!, these are literally the words he said while being interviewed on CNN.