No green screen on the burial. It really happened.
KF may be in on it, but MJ had to fool the world, so maybe he realized he had to also fool those who were once close to him. Remember he fired KF in 2006, but brought her back for the TII tour. I would guess she had not seen him in a long time when he called her to come back on tour with him.
So I think she's telling the truth when she says she did his makeup, but it took 9 hours to make him look like anything close to what MJ looked like. To her he was this sick, frail, skinny, victimized drug addict so yeah, he would look different than the MJ she knew in 2006. But the truth is, it wasn't MJ, it was his double and a double who could even fool those close to him.
MJ knew KF well enough to maybe not let her in on the hoax, but use her highly emotional personaility to feed the hoax.