Poland was a backwards power with little industry. Their military threat to the Germans was minimum.
There is little to no evidence of this.
Why wouldn't he? What reason would there be to wait? Hitler would have wanted to get at the Soviets as quickly as possible while the Red Army was still weak. He had no reason to wait, save on a bet that the Wehrmacht might grow stronger faster than the Red Army, and that's a bet I doubt he would have taken.
After Poland became obstinate and a puppet for Anglo-French interests there was little hope of Hitler acquiring any sort of military cooperation from them, meaning that to get at the Soviet Union they would have to be invaded at some point. Given Hitler's confidence and pattern of invasions beforehand, by 1939 he would have little reason to postpone an invasion of Poland and call the British/French bluff.
The problems with this is that either Hitler — and Germany — were so brash and pigheaded that they immediately invaded instead of seeking peaceful negotiations as a first option or expected not to have his concerns heard which, given the Munich Agreement and Hitler's familiarity with the Anglo-French willingness to talk, seems like an untenable view. The supposed atrocities — of which there is poor evidence of Holocaust-tier quality — occurred either after the invasion or so soon beforehand that it would be clear that no serious attempt at negotiation had been attempted. Hitler made a few proposals to the Poles close to the invasion date, but these were either unlikely to be accepted (military access through the Corridor is not something a country recently under occupation is going to jump at) or presented so close to the invasion that it is clearly not a serious proposal. The one commonly circulated on Holla Forums, for example, is dated the literal day before the invasion. That's not looking for resolutions, and lends itself more to a hasty justification for premeditated invasion than a legitimate outrage.
The poorly documented and far from established persecutions and abuses.
For a few centuries at most. It had been Pomeranian beforehand, and a mixture of Baltic, Germanic, and Slavic before that.
What about atrocities in a specific region requires the invasion and occupation of the whole country, much less an agreement beforehand with the Soviets over an invasion and division of Polish territory? That really doesn't add up.
"Non-aggression pact" doesn't equal alliance. Why wouldn't Hitler take a temporary guarantee with the Soviets? Or do you seriously believe that Hitler only planned to invade them post-1939?
I never said Hitler planned on Britain and France actually following through on their promises. I think Hitler took a bet that they would behave exactly as they had with Czechoslovakia, the Sudetenland, Austria, and the Rhineland before it. Hitler took a bet that the Anglo-French wouldn't interfere, and this time he lost that bet, necessitating him taking the risk of turning his back on his primary target.
I'm not even sure what you're trying to say here.