So, "если да - то да, если не нет - то нет" means basically that all negotiations are done and no more bargaining is accepted. All the sides of negotiations should stick with what they currently have agreement upon. If somebody still believes that something should be changed, then no deal.
So, it is #1 in your classification.
It's not a high style official business slang though. It sound like somebody was pretty fed up with negotiations ;)
Also, it worth to mention that the phrase "да - да, нет - нет" is actually Biblical, though is used in different context. It is from the Gospel of Matthew:
«Но да будет слово ваше: «да, да», «нет, нет»; а что сверх этого, то
This is what Jesus encouraged people to do - instead of making lenghty promises and obligations. Here's the English version of that excerpt:
Nor shall you make an oath by your head, for you cannot make one hair
white or black. But let your statement be, 'Yes, yes ' or 'No, no';
anything beyond these is of evil.