And about Hidan, we've never seen him do any jutsu's or hand seals, maybe thats a secret to his immortality trick too, all he ever does is use his killing/curse technique and taijutsu. Shikamaru though said that his chakra was increadible and hard to hold him with Kage Mane.
and to get back on topic Madara, just like everyone else in Akatsuki, has some way of prolonging with life. Maybe its like Samurai Champloo where they eat Wasabi plants and preserve themselves like specimen's in a jar of famaldihide, could be how Sasori has kept his heart alive all this time too, you can technically keep body parts a live for a really long time seperately its when they are all working towards keeping you alive and start failing one by one that you die. Like when doctors do live body organ harvesting the person is technically dead (the brain has stoped functioning) but the heart is still beating and blood is still pumping for a little while so doctors can carve out the organs in good health rather than take um from a completely dead person, gross but necessary.