Unless you have a high end camera, this kind of lighting is going to put you in to >1 second exposures. You'll want a tripod for that. In general, you should be able to focus pretty easily by hand, but auto focus likely isn't going to be much help. You might have luck with contrast based AF, but it depends on how good your sensor is.
You'll have to experiment with shutter times, but most DSLRs can go up to 30 second exposures without issue and at those kinds of light levels, you should be fine well under 30 seconds even at ISO 100. Keep your ISO as high as you can to minimize noise, but be aware that any movement during the exposure will result in blurs where that movement occurred (assuming it is lit). Particularly in a city, this may end up resulting in wanting to use shorter exposures with a faster ISO simply so you can avoid unwanted movement in the scene.
Certainly shoot RAW to give yourself some room to adjust after the fact and if your camera has it, I'd also suggest using long exposure noise reduction to help reduce accumulated noise from the long exposure.
If you have the budget for it (or have one already) using the fastest lens you can will also help as it will let additional light in to the camera. If you are shooting on APS-C cameras you can get some pretty decent and cheap fast prime lenses for a couple hundred bucks.