The FEPOWs were terribly badly treated - and for alot their post traumatic stress disorder left them hopelessly disabled.
I think your 70k slave labour death figure is low - it could be 250k. no records were kept. It is said it was only army discipline which kept the army figures so low.
There has been the odd tv prog on the FEPOWS, and the ones who were ship wrecked and THEN (re)picked up by the Japanese, I feel terribly sorry for. Presumably they were so near death by this time, they didnt much care, even if they did know what they were facing.
and finally, the Japanese were so scared of allied POWs communicating with the armed forcsd in the event of an invasion of mainland Japan that they were planning to massacre all of them in Sep 1945. It was only the events of Aug 1945 which precluded this.