Its impossible to prove he is good. unless your a psychopath

The [non]existence of supernatural beings and realms inherently cannot be [dis]proven. That's the whole point of agnosticism, and, indirectly, of atheism.

So ... clearly were god to actually, for the very first time in human history, to step out from behind the curtain and truly reveal Himself, it would at least possible to evaluate whether he was good and just, and certainly, at that point, the existence of god would be proven, so everyone wins.

Existence can be proven, but not goodness. Thus the former would be easier. ‘Existence’ is objective. ‘Good’ is subjective.

Like many of the other people posting in answer to these questions I too say neither. For those who believe both questions are answered yes. For those who do not believe the answer to both questions is no. It is a matter of belief not logic or proof.

Neither can be proven scientifically

Neither is possible. The fictitious god of the Abrahamic religions is presented as evil as can be, and the portrayals in this fairy tale stress this point. There is no other evidence available, unless one considers the voices that talk to totally delusional schizophrenics.

God has big problems with anger management.

Well, l know I'm going to try not to piss him, her, it off! Him, her, it has a nasty temper. Easily offended ya know. ☺

It would be harder to prove that god exists, as it is impossible to prove a negative. The reason is that if god revealed himself, the burden of proof to justify his actions would be on him. And to do that he would have to reveal his plan to such an extent that it satisfied our judgement to the point where we both understood and forgave him for what he has to do to keep his plan running smoothly, which would be impossible in and of itself, as he created the plan that any five year old could do better at.

In the general case, (2) seems clearly harder to prove, since it has far more premises to defend. To prove that God exists, s/he/it would simply need to identify themselves, or any of a myriad of other possibilities depending on the precise nature of the proposed deity.

However, there's a great deal more argumentative work needed to prove that God is just: At a minimum, a cogent definition of "just" must be worked out, and then this definition shown to apply to whatever God was shown to exist. It's kind of convoluted.

It woold be more difficult to prove the existence of this god than to prove that she/he is a good god. If we see the behaviors, we could then make a judgement

Well. Without evidence the existence of any God is unprovable speculation, whilst any existing God could possibly have some logical reason for their actions. So I would say the former.