[wmcbrine]

One thing that kind of bugged me was Harrison's age.

Although only eight years have elapsed in real time since the show was cancelled, in-story it's stated as ten. So that's part of it.

Well, supposedly Kurt's father killed Angela's friend

That was just some bull**** that Kurt said. Kurt killed her. (To "protect" her from being abused by people like his father, supposedly. You might say that he had his own version of The Code -- more twisted, and he didn't stick to it well.)

when Kurt was a teenager.

I'm not sure how old Kurt was supposed to be; I think he witnessed his father abuse women long before he started killing. Anyway, canonically, Iris disappeared 25 years ago, when she was 16. (Fandom wiki says Kurt is 61; I dunno where this was stated. Clancy Brown is 63.)

 

[wmcbrine]

No, Deb could not be a "conscience" because Harrison never knew or met Deb.

Actually he did, although he only dimly remembers her. (This was mentioned in the show.)