Fire alarm has 3 black / white wires, 1 red?
The red is probably the comm conductor for linked units. It is a bit odd that there's only one, but it could simply be the first in the chain. Without knowing the entire circuit layout I can't speculate further. 

The extra blacks and whites are probably part of a lighting circuit on the same breaker. To connect your alarm you'd pigtail from each color.

Your mystery switches could be for switched outlets. Check for half-switched outlets where you'd expect end tables, for example.