Short answers, pulled from the story.
The battle started on the 16th of November 1942 when the Australian 7th Division crossed the Kumusi River. The battle concluded on the 22nd of January 1943 when the Japanese garrison was virtually starved into submission.
Lieutenant General Harukichi Hyakutake led the Japanese 17th Army which was responsible for the Solomon Islands campaign while Lieutenant General Hatazō Adachi commanded the 18th Army responsible for operations on mainland New Guinea. General Hitoshi Imamura mobilised to take overall command from the 16th of November 1942 as head of the 8th Area Army based at Rabaul.
Malaria was the greatest disease threat with 85 to 95 percent of all Allied soldiers carrying the infection during the battle. Other tropical diseases such as dengue fever, scrub typhus, tropical ulcers, dysentery, and fungal infections were also common due to the humid conditions and lack of effective medicine.
Allied forces faced critical shortages of ammunition and rations until landing strips were developed to support engaging forces. The Japanese garrison ran out of food by early January 1943 when their rice ration dropped to 40 or 80 mL per day leading to starvation before the battle ended on the 22nd of January.
Rain turned tracks into mud while temperatures reached extreme levels with humidity hitting 82 percent creating oppressive conditions. Kunai grass trapped heat and the area contained thick jungle and swamp dispersed through relatively open patches that hindered movement and visibility.