Why did he stop the order to attack a couple of times, telling the army he needs more time for negotiations?

Never heard of this, but even if true, it doesn't matter because he still attacked Poland unprovoked (unless you count the false-flag attack, of course).

Why did offer peace on September 2nd (this offer was presented to the British government this day) - before France and Britain had joined the war?

Offered peace?

Sorry, but he had already invaded Poland, and the UK had to honor the agreement.

The only 'peace offering' he could have made was asking the Brits to stand down and betray their allies — and obviously they weren't going to do it this time.

Yeah, because Poland wanted German territory

I don't even want to know where you read this, but even if true — which I'm sure isn't — it's still a piss-poor excuse for aggression. Up until 1939 Germany had been scaring the shit out of Europe, and you want me to believe that Poland and its pathetic army wanted to challenge German might?

Britain wanted to keep "the balance of power"

Britain tried to appease Hitler and fulfilled his every demand up until 1939. What they wanted was avoiding another war.

He literally cites them in his declaration of war.

You didn't get my point.

I was asking why did Germany have to conduct a false-flag attack and murder its own citizens if the Poles had previously done something similar.

Because Poland wanted to gain more territory and cleanse "their" country from foreigners (Ukrainians, Germans, etc.).

Poland had a right to do whatever it wanted within its territory and nobody would have cared.

Those were different times; there was no global police force like NATO that intervened to stop poor minorities from persecution (something-something-Serbia).

So why did London refuse to host a conference with regards to the Danzig question?

Look, as I've already mentioned, I don't know if what you're saying is true.

But even if I once again take your word for it, the UK simply might have had enough with Hitler's bullshit and expansionist policies and didn't want to surrender anything else to him.

Remember, they had already kept a blind eye on Rhineland, end of the Treaty of Versaille, Ruhr and so on.

tell Warsaw to not negotiate with Germany

What negotiations are you talking about?

Germans didn't even attempt to 'negotiate' with the Poles, they conducted Operation Himmler and launched an invasion.