Is the boy in the bubble still alive? siwoon's half brother?

What boy in the bubble?

in the hospital bed in earlier chapters at the Min family mansion, you know? he looks like siwon to me. Is it called "Min family? or "Min .. woon?" don't know. anyway, jiwook spied and saw him, right?

and also, who was in Joohoon's wallet photo?

If you're referring to Min Woojin's half brother the implication was that he died and instead of just introducing Min Woojin as the new heir of the family after his death they covered it up and they just replaced him with Woojin and just claimed he had miraculously recovered so they wouldn't have to admit that the new heir was a bastard. I think.