1) The symptoms could be due to old age, or having used Rinne Tensei without knowing the actual risks behind the technique. If he used Rinne Tensei, then i guess he wanted to revive Izuna to see him at least once, but his brother died too long ago to be resurrected, or maybe he managed to bring him back for some instants and talk to him about what happened of his sacrifice. Izuna could have been shaken, depressed by the news from his brother and that made Madara feel even more guilty, so he decided to create a moon eye plan. Who know? Maybe Izuna told his brother that he had a descendant nobody knew about, and he asked Madara to take care of him. Madara then traced the uchiha clan tree to see who would this boy be, and it turned out to be Obito. So he saved him to respect his brother's wish, before he died again.
2)Lol, i think the place, is an earthly location. A hideout, yeah. "Being between life and death" refers to Obito's severe conditions here. That's my guess.