Short answers, pulled from the story.
The Battle of Rehe was the second part of Operation Nekka, a Japanese military campaign to capture the Inner Mongolian province of Rehe from warlord Zhang Xueliang. It was fought from the 23rd of February to the 4th of March, 1933, ending with Japan seizing Rehe's capital, Chengde.
Japan aimed to secure the southern frontier of Manchukuo, the new Japanese-backed state, after already seizing Shanhaiguan Pass at the Great Wall in January 1933. Japanese strategists declared Rehe to be historically part of Manchuria, providing justification for annexing it to Manchukuo.
Chinese forces numbering between 100,000 and 150,000 were assembled to defend Rehe, drawn from three separate commands: 40,000 under Wan Fulin, 30,000 to 50,000 under Tang Yulin, and 30,000 former Guominjun soldiers under Sun Dianying and Song Zheyuan.
Zhang Xueliang was forced by the Kuomintang government to relinquish his posts following the Chinese defeat. The official reason given was "medical reasons."
The Tanggu Truce was a ceasefire agreement reached after Chinese forces retreated to the Great Wall following the fall of Rehe. It established a demilitarized zone between the Great Wall and Beijing. The arrangement proved temporary, as full-scale fighting between Japan and China resumed with the Second Sino-Japanese War in 1937.
Yes. The Japanese Army's chief of staff sought Hirohito's sanction for the operation, and the Emperor approved it while explicitly stating that the army was not to advance beyond China's Great Wall. Hirohito hoped it would be the final Japanese operation in the region.