"It's not HUNK, he's about 50 in this. New guy is confirmed to be a new character for younger players to relate to"
You know, if HUNK is indeed Alex Wesker, then he'd be immortal. Just look at Tuck Everlasting, or anything about Immortality. I think the kid was like over 100, yet he still retained his youthful appearance. Maybe it's the same deal with HUNK?
Alex Wesker creates Immortality Virus and uses it on himself. Alex disappears. HUNK joins the USS, little to nothing is known about him. HUNK is nicknamed Mr. Death because the "Death Cannot Die".
Wanna know why the Merc guy's blood is so valuable? It's because he's Alex Wesker, and his blood is the key to stopping the viruses. Steve's blood contained T-Veronica, not something that would save everyone. (Although, Steve's blood would be good as a fire-starter :p)