I am like 95% sure that luffy will die EOS.
Nope
Oda already said once that One piece has happy ending.
Second, him recovering energy is simply adrenaline boost because he is pumping more blood.
Luffy df is actually working like as if all his body and organs are rubber....
He is using his rubber heart to pump more blood.
Using elasticity of rubber to make weird faces
Using rubber elasticity to expand at his will.
Only catch is that he is also zoan