Hmm, I'll have to read up more on this, but I'm going with A&P's version for now which makes more sense and is an acknowledged authoritative.
See http://www.history.army.mil/books/70-7_04.htm for a description of the development of Japanese warplans before WWII. Note that it does not contradict in fact any of your sources, only the unwarranted assumption that just because Nagano personally opposed war with the U.S. (as did Yamamoto!), that represents the view of the Japanese high command, or had any chance of being put into practice no matter what Yamamoto does.
Fact is, Japan had already decided at the highest levels that it must use force to break the ABCD embargo, and that it could not afford to strike at the DEI without first neutralizing the British and American holdings in the area.
Had they not done so, they could have, ya' know, fought a limited war, actually bring their home advantages to bear and actually make an armistice possible? People tend to forget that the USN of 1941-42 wasn't the top-grade stuff that came later in '43 or '44, and that the Combined Fleet Striking Force had the best coordinated aerial strike force at the time.
Define limited war. There was no chance in hell that Japan would let the U.S. keep a base from which it could choke off the oil spigot from Indonesia at will, despite Nagano's wishful thinking. And it is wishful thinking. The U.S. would never have accepted Japan using military force against the U.S. led embargo, in direct defiance of the U.S. ultimatum, and it is likely to be more despite FDR rather than because of him. FDR was very much focused on Europe and wished to keep the peace in the Pacific to free up resources. He was roundly criticized for not being sufficiently hardline over the Panay incident, and also for transfering 1/3 of Pacific Fleet to the Atlantic for Neutrality Patrols, including 2 carriers and 3 battleships, due to the perception that it showed weakness.
As per the Japanese plans pushed by the General Staff and approved by Admiral Nagano, Japan would have opened with surprise attacks against the Philippines, which OTL was overshadowed by Pearl Harbor, but still was one of the greatest military disasters in U.S. history and would be viewed as such TTL, likely even as a Day of Infamy. They then would have proceeded with the same historical centrifugal offensive, only perhaps moving slightly faster due to having the Kidou Butai and its supporting shipping available from day one. On the other hand, without the defenses of PH in ruins, the U.S. has hundreds of modern aircraft that historically went to rebuilding Hawaiian defenses that could now go to Australia. The Wake relief operation would likely have gone ahead with a well defended base and battleline to fall back on and without the U.S. command having had its nerve shattered, meaning Wake remains in U.S. control. At which point Japan ends up in a notably weaker position than historically at the same time, and there's not even any reason to believe the U.S. would be noticibly less determined.