a) is untrue, Shaq got 121 million from the lakers. Orlando's last offer was 130 million based on numerous reports at the time. I'l give you the first link there are dozens of them that say the same thing.
http://www.nytimes.com/1996/07/19/sports/pro-basketball-lakers-get-o-neal-in-7-year-contract.html
The Lakers original offer was 95 million, Orlando topped it offering 115. The lakers traded George Lynch and Peeler to up their offer to 121 and Orlando offered 130 and said Shaq never responded to the final offer, told them by voicemail he wanted to play for a team with a better tradition of winning and that was the Lakers.
I agree about the market and endorsements part.
And yes I think Shaq told the truth last year, he was already doing movies he'd starred in 2 before he even joined the Lakers. He was already a top endorser he already had pepsi and reebok deals. He'd already done rap albums and tv shows. Yes being in LA allowed him to do more of that but it was already available to him. He went to LA for the reason he said the day he signed, LA had a longer tradition of winning and having dominant centers and he wanted to be part of that.