I still don't know what Clemenza was referring to in GF1 when he goes "the negotiator is playing pinochle, he's happy, they're letting him win"..then he goes "the negotiatior keeps playing until (I forget who he says) comes home safe and sound". What is he referring to?

The novel talks about the Bocchicchio clan that was in the business of providing hostages (negotiators) in such situations. While Mike is meeting with Sollozzo, a Bocchicchio is in the Coreleone's hands. If something happens to Mike, the Bocchicchio gets killed, then the Bocchicchios go after Sollozzo.

Yes, and this is a perfect example of where an important detail laid out in the novel causes confusion because it wasn't included in the film. Nobody would know what Clemenza was referring to unless they read the novel. The Bocchicchio Family, and the role they played not only in negotiations but in bringing Michael back from Sicily, is one of the best side stories in the novel.

This brings up a question. The Corleones insisted that they have a negotiator to protect Michael's safety during the Solozzo meeting, but Sollozzo apparently did not do that...why not? Certainly he suspected Michael could do him harm because he had McCluskey frisk him in the car and he briefly frisked Michael after he relunctantly and with suspicion permitted him to go to the bathroom.

What do you mean? The Corleones do have a negotiator already. He's playing pinochle with Clemenza's men.

Despite having Michael patted down in the car and thrusting his hand in his crotch prior to giving Michael permission to go to the john, Sollozzo fundamentally underestimated Michael. He thought that Michael, a respectable college boy and "civilian," wouldn't have the nerve or the cunning to attempt an assassination, especially with McCluskey at his side.

The novel provides more illumination. After Michael shocks Sonny et al by proposing that he kill S&M, Sonny says, "And now Sollozzo has you figured for the soft touch in the family because you let McCluskey hit you without fighting back and you wouldn't get mixed up in Family fights..."

As the novel points out, Sollozzo knew he couldn't ask the Corleones to guarantee his safety.

As pointed out in the film, a police captain was considered "untouchable". Nobody had ever considered taking one out, so Sollozzo was convinced of his complete and total safety.

Still, Sollozzo took many precautions. He tried to conceal the location of the meeting, he had his driver head to New Jersey before the famous U Turn and he had Michael frisked, so he had to think he had some level of vulnerability, even if , say when Michael went to the bathroom someone ame by and hit them. So why would he not have a negotiator, after all he WAS "the hunted one." Maybe he just really was not that clevah.

To quote the novel, Sonny says "The negotiator guarantees Mike's safety. Sollozzo doesn't ask us to guarantee his safety, he knows he can't ask that. No point."

Perhaps one of the reasons was that, considering the mortal riskiness of the Bocchicchios' business, they accepted commissions only from established Mafia families--not from every Tom, Dick and Virgil.

Probably.

Maybe they didn't like Turks