How did these guys get clothes & food .?
Did they wear same clothes for 29 years ?
They would scrounge and steal food and supplies (presumably including clothing) from the people who lived on the islands.
They stole what they needed from the locals and foraged what they could from the jungles. The Japanese were well trained in foraging – especially since resupply was difficult even in the earliest stages of the war.
I don’t know if they still had their uniform. If they did, they probably stopped wearing it on a daily basis and saved it for some future important occasion.