They did Elliot dirty

I have few questions:

1. Who really killed JFK? It seems like Regi did not really kill him cause when he met with his friends or group he was upset that JFK died. It also couldn’t be the older number 5 cause he went in the portal.

2. So The new Ben cannot remember everything they did with the original siblings? Like he was wiped clean? He’s a new and different Ben as if he did not die as he was supposed to?

3. I am so disappointed at number 5 for not seeing or figuring out that them causing so much in the 1960s (civil rights movement, elliot’s death, death of sissy’s husband etc) has a lot of repercussions and consequences in the future. All their actions during their stay in the 1960s would somehow alter and affect the future. Number 5 is supposed to be smart and calculating guess he forgot about this one. What happened to him?

4. Why did the writers made Diego dumb and erratic this season? It’s like a different Diego from season 1. They threw his character development from season 1 from sparing Cha cha’s life.

5. And lastly, THEY DID ELLIOT DIRTY! WHY DID THEY KILL HIM OFF JUST LIKE THAT? HE WAS JUST TRYING TO HELP THE GROUP! HE WAS BEING HELPFUL AND SWEET TO THEM AND THEY KILLED HIM LIKE THAT? HIS STORY ABOUT HIS WIFE AND BFF MADE IT EVEN SADDER!! HIS DEATH BETTER HAVE REPERCUSSIONS IN THE NEW TIMELINE