Base on my limited understanding, sensor has certain threshold limitation (sensitivity), to detect how much light fall onto each of the photosites (pixel). And when light is low, each of the pixel will not capture the exact light intensity and color, so the sensor will start to do 'guess' what the light intensity/color it should be. As a result, either details that suppose to be there were lost, or wrong color is interpreted, and the end result is the 'noise'.
On your second question, G9 has a 'firework' mode (go to scene mode), which you can choose and it should help you with the auto setting, but make sure you have a tripod or good camera support.
Background image to be blur... Are you refering to motion blur or 'bokeh' ? Motion blur happens when there is relative motion between your subject and background. It's easy if your subject is stationary, just ensure it's long exposure (0.5 second or longer, depending on the effect you want), and your camera is stationary (on tripod). If your subject is moving, that will require 'panning' skill for you to trace the subject with your camera while keeping the shutter speed low (0.5 sec or longer).
If you're asking about 'background blur', like those effect you see on portrait shoots where background is blur-off and the subject is sharp, the blur effect is normally call 'bokeh', and it's a very big subject in the serious photographer field. Unfortunately, G9 won't be able to produce a very good 'blur' effect, due to the small sensor size and the small max apperture (the reason why will be a long long discussion). In order to achieve the maximum blur background effect, you should zoom all the way in (optical zoom only please), and keep the max apperture f4.8 at longest zoom end, that should give you some blur effect on your background. If you want anything more, DLSR and a 'fast lens' is what you need.
Not sure why you want the item to be blur and background to be clear, but you just simply reverse the rule in the previous case, your background become your subject now...
Just experiment and have fun !