Factual back-up, sources, and further research materials.
Regarding the first point:
From 2006: FBI says, "No hard evidence connecting Bin Laden to 9/11"
911myths.com states that Betsy Glick in the FBI Public Affairs office told them that, "The information provided at that time by the (now retired) Investigative Publicity Unit Chief, who was not an agent nor a counterterrorism expert, does not accurately explain the situation."
Contradictory statements aside, in 2001 then Secretary of State Colin Powell stated that the government would soon "put out a paper ... that will describe clearly the evidence that we have linking" bin Laden to 9/11. One day later the government reneged on this pledge and no such paper has ever been offered. So it seems that the first statement from the FBI was the honest one. Bin Laden has admitted to being involved in 9/11, but just like the FBI he has made contraduictory statements and denied his guilt on three reported occasions, including once on video, but this doesn't mean he wasn't involved. Afterall, there is circumstantial evidence against him in the form of a video showing him meeting with with some of the hijackers. And as 911myths.com points out, "Since 9/11, al-Qaeda have released footage of several of the hijackers. These include a number of video wills, where they talk about jihad and attacking America."
Mechanical engineer Tony Szamboti had this to say at 911 Blogger:
The much bigger issue than when he died is that Osama bin Laden was not wanted for the 911 attacks by the FBI. The video of him allegedly admitting to it was found like a needle in a haystack in a house in Jalalabad, Afghanistan in Dec. 2001, after the invasion. The FBI apparently had a problem with that video as it did not deem it as grounds to indict bin Laden for the 911 attacks.The evidence indicates the problem the FBI has with the tape is that it proves, as 9/11 researcher Ed Hass wrote in 2007, that the tape was obtained in a CIA string operation and thus "the CIA had Osama bin Laden in its sights, camera and rifle, on or about September 26, 2001 and failed to capture or kill him in favor of gaining a videotape confession of sorts to support the Bush Administration’s invasion of Afghanistan and Iraq. If Osama bin Laden had been captured or killed on or about September 26, 2001 – there would have been no international support for the U.S. invasion of Afghanistan." Click here for more info.
Shortly after 911 Colin Powell said a white paper would be released which proved the guilt of bin Laden for the 911 attacks. Incredibly, no white paper was ever provided to the public...
Bottom line, bin Laden and Al-Qaeda hijackers being involved in 9/11 in no way negates the slew of evidence indicating the attacks involved inside help.
Related:
President Obama: 9/11 Families Ask You to Watch “9/11: Explosive Evidence - Experts Speak Out”
Scootle's "Twenty Minutes With The President" Contest Entry
