Regarding Madara, Kabuto tweaked him around, remember?? the remark Kabuto made about perfecting ET culminated in Madara's current form.
Thanks for answering me, Codus. I do remember Kabuto saying he perfected the ET, and that Madara has been adjusted, but I just don't see / remember how that would have affected ET!Madara's youthful appearance. I guess it doesn't really matter either way. It appears Madara did live a long time, and the specifics of how the ET was changed for Madara are to be accepted on face value -- like so many other technical details in this story.
No, it is almost certainly impossible. Losing a lot of blood in a short amount of time would reduce the overall blood pressure dramatically, sending the body into shock, and therefore losing consciousness. Unless you have a blood transfusion, you would almost certainly die. But that is real life.
As I posted several pages ago, there are documented cases of human beings surviving injuries much like what Tsunade has now endured, either temporarily or, in rare cases, permanently. In such cases, the conditions are just right that rapid blood loss, subsequent loss of consciousness, and immediate cascading organ failure does not occur. The location of the injury and/or the weight and consistent pressure of the severing object prevents it. A certain stability can be achieved -- for a while, anyway -- until the severing object is removed. That's when the person normally bleeds out and organs fail, etc.
In a story chock full of fantastical physiological elements -- bloodline limits, hosting tailed beasts within the human body, battlefield eye transplants, rampant DNA experimentation and modification, turning the human arm into a lightning blade, Mokuton (need I say more?), etc. -- what Kishimoto has done with Tsunade is the least unrealistic and implausible, as it lands squarely within the realm of real world possibility by comparison.
I wonder if it's to one-up himself. He already had her run through the gut and she lived from that. So maybe he feels he needs an injury she cannot undo with that particular jutsu. The deal with the slug makes her look a bit heroic (don't worry about me, save them), but yeah, a lot of characters see to come with some assembly required and the slug is rather....unfazed for seeing such an injury. The frogs would be spazzing if they saw that.
Later I got to thinking about Tsunade's speech regarding the rule for medical nins not getting involved in the fighting. She disregarded her own rule, and now she's nearly incapacitated and has put her ability to perform her prime function at risk. She's going to use what's left of her chakra to save the other Kage first, and then if there's anything left... well, it's anyone's guess.