There are a number of questions you have posed so I'll try and give my opinion to them.
I like the basic concept of your image, for me there is a bit too much tunnel wall its taking up almost 1/2 the image so I'd be looking at possibly moving the frame over to the right. This would also bring the canal down towards the bottom right corner which I think would help you lead in lines.
Your settings have produced a reasonable image, however at night I would recommend the smallest aperture should be f/11 this is the because most lenses are at there sharpest and best between f/8 and f/11. For night photography I would say the amount of light reaching the sensor is your most important priority so I would use an aperture of about f/5 to f/5.6 and use an ISO of 100 to help reduce noise as much as possible. Other people commenting on these settings will have their own formulae and preferences just because you are adjusting 3 variable, the best thing to do is take a series of images at different settings and choose the best.
You ask about B+W, this again is down to personal preference, how dark should shadows be answer as dark as you want them to best compliment your image. using Silver Efex is a good way to create a B+W as many adjustments are made in the presets so its choose the best looking. Away from Silver Efex converting in Photoshop etc, I would make sure Black is black and white is white then set a midtone level which pleases you.
Sorry I can't be more helpful with B+W but it is all personal taste and ensuring you have good contrast.
One final point I think your lights are quite over exposed for this shot so it may be possible to reduce the exposure slightly. If you shoot in RAW take a slightly overexposed shot and then reduce the exposure in the processing to get the level you like and only convert to B+W after you have set the levels in a colour image.