If we decide to sign a contract with you, we will need to.... This is type 1 conditional sentence and this sentence doesn't mean that you have already decided to sign the contract.

If it's 50/50, you should say: If we decide to sign a contract with you, we will have to find out the following ... In if clause you use Present Simple, in the main clause- Future Simple!!!

If I decide to sign a contract with you, we FIRST need to AGREE on the following points: 1) .. 2) .. etc.. If we decide to sign the contract, we need to AGREE on the following points: 1) .. 2) .. etc.. If I decided to sign a contract with you, IT WOULD BE only after we AGREE on the following points: 1) .. 2) .. etc.. we'll decide, on the contract details when we have AGREED on the following points: 1) .. 2) .. etc..

Although it is not correct English as written, it would be understood. In English, the word "if" is a powerful word that sends a unmistakable message. It's the important word. You won't accidentally reverse its meaning by choosing the wrong verb form. It's best if the rest of the grammar is correct and matches the "if," but what you wrote is clear. As others have said, one correct form is "If we sign a contract with you, we'll need to find out..." I can't explain it, but we need the idea of the future in the second part, "we will need to" or "we'l need to," but we don't use it in the first part.