Thefocus mode (center, select, auto) won't make a difference if the camera isn't functioning properly. If the camera IS functioning properly, then the auto mode can lead the camera to focus on something you didn't intend sometimes (it chooses a different subject in a different place than what you had in mind). I avoid auto and use select or center.
Usually the term "spot" is used for metering, rather than for focusing - spot vs. center-weighted vs. matrix. This doesn't have anything to do with focusing, onlymetering for exposure settings(and for some reason, I had the hardest time keeping them straight and separate in my mind).