I didn't read the entire thread, but I have taken plenty of night shots...
Turn down the NR to minimum and use post-process NR instead, but that is NOT to be confused with NR which is "Dark Frame Subtraction". That is when the camera takes an equal-length exposure with the shutter closed and subtracts it from the original exposure. Dark Frame Subtraction is necessary to eliminate noise from pixel sensitivity differences. Preferably process RAW, but Sony is in a class of its own for direct JPG output without much need for RAW processing, if not going to stretch the final image to extremes.
Taking night shots of distant lights requires very careful exposures, and typically three of them combined to create a HDR image. The image you took would be especially difficult as the skies are very dark, but the lights are, well, very bright. So take three shots 2/3 a stop apart and combine them with HDR software.
Otherwise just increase your exposure time, and who cares if the lights are blown highlights. That isn't the interesting part anyhow.
Yes, keep the IS off when tripod mounting. Mechanically these can only compensate for the relatively slow shake of a camera in a person's hand. they are optimized for this scenario. When you mount a camera to a tripod, the mode of resonance is much higher, and the IS is unable to cope, making any camera shake worse.
Use the timer function to start your exposure. The same one used for portraits where it gives you time to run into the frame. Prevents motion caused by depressing the shutter button.
Use a remote, no touching the camera at all.
Digital exposures are "free". Expect to take many night shots and hope a few com out well. It is difficult sometimes to gauge the exposure for the desired effect. I have overdone moonlight shots that look like daylight, but that is not what I wanted to portray. Anyhow, have fun, night shots are technically difficult in some locations, but rewarding when you get something nice!
Some samples, not all "perfect" but fun. Tried to capture the mood of the experience of sitting in a warm field watching fireflies and listening intently for the rustle of coyotes sneaking up on you. Keeps things exciting.http://picasaweb.google.com/wymanfamily3/Fireflies2#http://picasaweb.google.com/wymanfamily3/FireFlies#
These were especially hard in some cases, since I have almost no light scatter. Almost pitch-dark to where you cannot see your hand in front of your face. So it is really cool when you can see something after the exposures.