It sounds like new batteries may have fixed the problem.
You say you are no longer getting extreme brights/darks.
Check the battery compartment and see if there is any corrosion from the previous batteries.
Corrosion shows up as white or green powder on the metal parts.
If it is there, it must be cleaned out.
If you are using standard batteries, make sure you are using Alkaline batteries.
Regarding the changing flower and mountain symbol.
That is normal if you are in Smart Capture mode.
Put it in P,A,S,or M mode and you will see that it will stay where you put it when you use the Focus button on top of the camera.
When you are in Smart Capture mode the symbols will change as you point the camera at something far (mountain) or close-up (flower). It is changing because you are moving the camera around. Keep the camera still and the symbol will stay.
Regarding the poor quality problem.
Most likely it is caused by the digital zoom.
Look in the set-up menu and make sure that the "advanced digital zoom" is turned off.
Digital zoom degrades the quality of a picture.
I'm not sure what he meant by bracketing.
I do not know what a man with brackets is.