So on my second character, I'm wondering if as soon as I get to the Institute, I can blow Father's head off and still work with the railroad afterwards? My character is convinced that her son is dead, and this creepy old guy saying he's her son would just make her fly off the edge. At the same time though, I'd like her to work with the railroad as she seems like she'd fit in well with that hodgepodge ensemble of weirdos.

If you're banished from the Institute, it cuts off the Railroad questline, sadly. But you can still be friendly with them and advance their goals with the Minutemen.

Can I still use Deacon as a companion if I get banished from the institute? I had to kill him as my first character, never used him as a companion, but I hear he's funny.

You may, yes; you just need to complete Tradecraft first.

Cool, thanks. Kinda svcks that I won't be able to get the railroad ending though.

Yeah, I was just as shocked when I learned that one. The only hope I have to completing the game for one of my characters is to do Garvey's hell-level annoyance that is his endless settlement quests. :[ Dammit! Guess I'll have to roll another character and make that one my RailRoad character. Dammit.

The Minutemen ending is basically the same as the Railroad ending, I believe, except that Liam Binet doesn't commit suicide. Also, you don't have to kill anyone in the Brotherhood.

Preston Garvey does run out of quests eventually too.