FS means is DA/SA, but the satey works as both a saftey AND a decocker.
The G is also SA/DA, but the safety is ONLY a decocker. Once you flip the safety, it drops the hammer and then the saftey switch itself goes back into the fire position. Many people prefer this because they are afraid that the safety may get hit by accident, and then the gun would be stuck in "safe mode" without their knowledge.
The FS was always fine with me, personally. I rarely ever used the safety, and it never got hooked on anything when I used a 92FS.
The DAO is only double action.
And, unless you buy one of the more rare, esxpensive models with a frame mounted safety, there is no was to carry the gun in condition 1 safely.