Hi Kpzen,
I'm gonna try to answer a few of your questions, largely based on my opinion so dont take it as the truth.
Cause of worry -
Well let me just say that IMO, if you want to take good pictures on a pro/consumer digicam, STAY AWAY FROM THE NIGHT PICTURES!
LIGHT is very important when it comes to capturing a good image, as well as helping the camera out with focus, exposure, whitebalance etc, none of which you can do as well with flash photography.
BSS
I have only played with BSS once on the latest EXLIM so maybe it had more options than yours. After hitting BS you select the type of photo you are about to take (snow, portrait, landscape, fireworks, candlelit, blah, blah) and depending on that it selects the appropriate aperture, ISO, shutter speed etc etc. Since it seems like in your camera you dont get the option of selecting the type of scene, READ THE MANUAL
Exp +/- , that will just over or under expose your auto exposure by the setting u choose. Neccessary if you are for eg. taking a shot of a tree with a very bright sky, which causes the tree to show up really dark, you would over expose causing the sky to be over exposed but the tree to be correctly exposed.
Difference between Normal and High of the same Resolution -
Its a matter of JPEG compression. Normal uses a more effective level of compression than High. As a result, file sizes are smaller, but in most cases there will be slightly more "compression noise" in the pictures, although, in most cases that slight difference is so slight that you do not notice it unless you zoom in 400% or more!
Moral of the story - shoot at "Normal", it will save you MBs or GIGs in the long run, unless you are shooting for something like a very large print, or your daughters wedding or something (even that is a ?able)
White balance -
Look it up online, i'm lazy.
Vivid and standard -
Just enhances/saturates the colours. Serious photographers will prefere to shoot on standard (and then do the neccessary saturating in photoshop or the likes), but for everyday users they may be more happy with the vivid colours when shooting in vivid mode. Try a comparison in bright light with something colourful and you will see what i mean.
cya
R