Wow, thank you for the long review! Especially for such an old game: it's been a while since I got comments on it! Besides, it's refreshing reading your actual feelings while playing the game, so it really makes my day!
Now, for your answers: there aren't more endings, and I think you've got everything, sorry.
I think you'll like the short stories in pdf, because they focus on the four friends doing silly stuff together at school (celebrating Halloween, Valentine's Day, and Easter), and that seems to be the part of A Hand in the Darkness you enjoyed the most (me too, if I'm being honest).
The first route I wrote was indeed Damian's, followed by Monty's and then Rick's. I'm a sucker for historic drama, so I wanted to make a story like the typical ones in Japanese yaoi manga, but set in the West and maybe with more realistic relationships. Hence the high school setting that got the game banned from Steam! XDD Well, the story is about coming-of-age, first loves, and friendship above all, so I don't think any other setting would work better for it.
And, finally... good luck getting the After Stories from other sites! I haven't seen them around, which I'm grateful for, and I think I've only seen one gameplay on youtube for them, and it was in Spanish, so I'm really sorry. Anyway, they are inexpensive, so I hope you can get them in the future. Thank you again for playing and for your kind words!