Why point your light_environment straight down? Usually an angle creates much more interesting shadows... anyway, you can use other light entities to cast light on walls wherever you need them to. Don't use multiple light_environments, that's of no use: one will cause every sky brush to emit light like defined in there.
A func_train can follow a chain of path_corners, it's quite easy once you figure it out. Check
Akilling.org for some interesting tutorials - there's about 3 or 4 about trains on the main page alone already.
As far as I know camera's aren't made to show players. Maybe there's a workaround or such, but I wouldn't give it much chance.